A new archaeological investigation of a monumental Viking Age ship burial in Norway has uncovered evidence that the grave may have been constructed on top of a much older burial mound. Archaeologists examining Grønhaug on the island of Karmøy have found traces that could date back to the Bronze Age, potentially confirming a theory first proposed a century ago.
The five-day investigation took place earlier this month at Grønhaug, a massive burial mound in Rogaland, southwestern Norway. Archaeologists from the Archaeological Museum at the University of Stavanger carried out the work on behalf of Norwegian cultural heritage authorities and in collaboration with Rogaland County Municipality.
Grønhaug was last excavated in 1902, when archaeologist Haakon Shetelig discovered the remains of a Viking Age ship burial. This time, researchers went deeper than Shetelig had and encountered evidence of an earlier structure beneath the Viking Age remains.
“We have received answers to the goal of this excavation, which was about the preservation conditions in the mound. In addition, several unexpected discoveries have been made, so we will find out much more than expected,” says Marie Ødegaard, associate professor of archaeology at the Archaeological Museum in Stavanger.
The results could shed new light not only on the Viking Age burial, but also on a landscape that had been associated with powerful elites for many centuries before the Vikings.
A Viking grave built over an older burial?
The Grønhaug site. Photo: Øyvind Nesvåg, Rogaland County Municipality
Grønhaug is located close to Reheia, one of Norway’s largest Bronze Age burial grounds. The mound measures about 30 metres across and four metres high and was constructed using bog soil and peat, with a core of pebbles surrounding the location of the ship.
Its position among much older monumental burials has long raised questions about whether Grønhaug itself originated before the Viking Age.
When Shetelig investigated the mound 124 years ago, he excavated only part of it. He later wanted to return to Grønhaug in 1926, in part because he suspected that the mound had originally been constructed during the Bronze Age. That second excavation never took place.
A century later, archaeologists may finally have found evidence supporting his theory.
“Considering the Bronze Age landscape that Grønhaug is part of, it is likely that this was also a Bronze Age mound. Among other things, we have found the outer edge of what may be a Bronze Age grave, which lies lower in the ground than the traces from the Viking Age. We would not have thought that it would be so obvious that a Viking grave had been built on top of the older existing grave,” says Ødegaard.
The discovery does not yet prove that the earlier remains date from the Bronze Age. Samples collected during the excavation will now undergo further examination and dating, a process expected to take several months.
If confirmed, however, the discovery would show that those responsible for the Viking Age ship burial deliberately placed their monument within a landscape that had already been associated with monumental burial and displays of power for many centuries.
The wider Reheia landscape reinforces that possibility. Seven monumental Bronze Age burial mounds survive there, forming some of the earliest prominent displays of power along the Karmsundet waterway.
The Grønhaug ship burial
National Director of Antiquities Hanna Geiran (left) and Museum Director Kristin Armstrong-Oma at the Archaeological Museum at the University of Stavanger, show off some of the ship nails found in the mound. Photo: Øyvind Nesvåg, Rogaland County Municipality
The Viking Age burial at Grønhaug itself remains only partly understood. The oak ship found inside the mound measures approximately 15 metres long and 2.8 metres wide. The ship has been dated to around AD 864, although archaeologists believe the burial was created somewhat later.
“The Grønhaug shipwreck is interesting for many reasons,” says Håkon Reiersen, associate professor of archaeology at the Archaeological Museum, who is leading the investigation alongside Ødegaard. “Very little of this burial mound has been investigated. Dating the burial mound has been challenging. The ship dates to around the year 864, and the grave probably a little later, around the time Harald Fairhair took Avaldsnes into use as his royal seat. It has also been suggested that Grønhaug was Fairhair’s grave, but that is not the case.”
Avaldsnes, located nearby on Karmøy, became an important centre of royal power. Its location beside Karmsundet was particularly significant. The narrow waterway separates Karmøy from mainland Norway and formed an important maritime route along the country’s western coast.
The area’s archaeological remains indicate that control of this landscape had been important long before the Viking Age. Large and richly furnished burial mounds dating from the Bronze and Iron Ages demonstrate the presence of powerful elites around the waterway.
Grønhaug was also not the only ship burial constructed here. Nearby Storhaug contained another monumental ship burial, excavated in 1887. Recent research dates the Storhaug burial to AD 779, making it an early example of the monumental ship burial tradition that would later produce famous sites such as Oseberg and Gokstad.
Remarkable preservation inside the mound
Project leaders Marie Ødegaard and Håkon Reiersen show and explain a little about the discoveries they have made in a burial mound with unusually humid and good preservation conditions, which is a good starting point when dating the samples. Øyvind Nesvåg, Rogaland County Municipality
One of the principal aims of this month’s investigation was to determine how well archaeological material survives inside Grønhaug. Here, too, the results exceeded expectations.
The four archaeologists working at the site discovered birch bark, heather and pieces of wood believed to be more than 1,000 years old. Their survival indicates unusually favourable preservation conditions inside the mound.
Much of the ship itself also remains underground. The archaeologists deliberately placed their excavation trench several metres away from the surviving vessel, meaning that the new investigation did not involve reopening the ship burial itself.
That leaves open intriguing questions about what else might survive within Grønhaug.
“From other ship graves we know that, in addition to the ship itself, there were also small boats in some burial mounds,” says Reiersen. “There is actually a possibility that small boats may also be found here at Grønhaug,”
This is what it looked like in 1902, when Haakon Shetelig from Bergen Museum conducted the first archaeological excavation of Grønhaug. He wanted a new excavation in 1926, but nothing came of it. Photo courtesy University of Bergen.
The possibility is not without precedent on Karmøy. The nineteenth-century excavation of nearby Storhaug uncovered both a ship and a smaller boat, along with weapons, tools and luxury objects. The 1902 excavation at Grønhaug also produced evidence of the wealth invested in the burial. Among the finds were exclusive down and textiles from elaborate carpets.
“It may be possible to find such things here. However, that was not the goal this time, because we do not have the budget for that. The excavation nevertheless shows that it is possible to find magnificent, royal objects if it becomes necessary to conduct a new archaeological investigation in the burial mound,” Reiersen adds.
For now, archaeologists are leaving those potential discoveries underground. The purpose of the excavation was to understand the mound’s construction and preservation rather than undertake a large-scale investigation of the Viking grave.
Grønhaug and Norway’s Viking heritage
The burial mound was opened at a similar location in 1902, but this time the archaeologists have dug much deeper and found more answers. | Photographer: Håkon Reiersen, Archaeological Museum, University of Stavanger
The investigation also has a broader purpose. Norwegian heritage authorities are studying the country’s monumental Viking ship burial mounds as part of an effort that could eventually lead to a UNESCO World Heritage nomination.
In December 2025, Norway’s Directorate for Cultural Heritage recommended seven ship burial sites for inclusion on the country’s tentative list for World Heritage status.
The sites are Gjellestad in Østfold; Borrehaugene, Oseberghaugen and Gokstadhaugen in Vestfold; Storhaug in Rogaland; Myklebust in Vestland; and Herlaugshaugen in Trøndelag.
Storhaug’s inclusion makes the investigation of neighbouring Grønhaug particularly relevant, since researchers are increasingly considering these monuments as parts of wider cultural landscapes rather than simply as individual graves.
“The Viking Age is an important part of our history. The Viking ship graves are completely unique, and we believe they may have potential for a UNESCO nomination, and perhaps an inscription,” says National Heritage Commissioner Hanna Geiran.
The process remains at an early stage. Inclusion on Norway’s tentative list would not itself make the ship burial sites World Heritage Sites. The Norwegian government must first decide whether to proceed, after which a formal UNESCO nomination would require considerably more work.
“We are now carrying out an assignment on behalf of the Ministry of Climate and Environment for UNESCO’s tentative list. The government will decide whether we will proceed with the nomination. If that happens, it is an extensive process that will take time. But this excavation is an important step on the way,” says Geiran.
Norwegian heritage authorities argue that the monumental ship burials are important evidence for understanding Viking Age power, society and beliefs about death. The mounds themselves were enormous undertakings, requiring substantial resources and labour while creating highly visible monuments in the landscape.
At Karmøy, that landscape may now prove to have an even longer history than previously understood.
Waiting for the dates
Archaeologists Kristoffer Hillesland, Marie Ødegaard, Håkon Reiersen and Theo Gil Bell from the Archaeological Museum carried out the excavation of Grønhaug in 2026, with good help from excavator driver Simon Knutsen.
The excavation at Grønhaug was completed after five days, but the archaeological investigation is far from finished. Researchers will spend the coming months examining the samples taken from the mound and attempting to establish more precise dates for its different layers.
Those results will be particularly important for determining whether the structure discovered beneath the Viking Age burial really does belong to the Bronze Age.
If it does, Grønhaug would preserve evidence of two very different periods of monumental burial at the same location: an earlier mound created within Karmøy’s Bronze Age landscape and a spectacular ship burial constructed there more than a thousand years later.
Before closing the excavation, the archaeologists added one more layer to Grønhaug’s long history. They left behind a letter addressed to archaeologists of the future, accompanied by a glass cup from Avaldsnes, several coins and a candle.
The archaeologists’ letter to the future, after a week of excavation of Grønhaug in Karmøy. Photo: Håkon Reiersen, Archaeological Museum, UiS
More than a century separated Shetelig’s investigation from the latest excavation. If Grønhaug is opened again far in the future, the next archaeologists to investigate the mound will find a small archaeological deposit left deliberately by their predecessors in 2026.
Top Image: Photo by Øyvind Nesvåg, Rogaland County Municipality
A new archaeological investigation of a monumental Viking Age ship burial in Norway has uncovered evidence that the grave may have been constructed on top of a much older burial mound. Archaeologists examining Grønhaug on the island of Karmøy have found traces that could date back to the Bronze Age, potentially confirming a theory first proposed a century ago.
The five-day investigation took place earlier this month at Grønhaug, a massive burial mound in Rogaland, southwestern Norway. Archaeologists from the Archaeological Museum at the University of Stavanger carried out the work on behalf of Norwegian cultural heritage authorities and in collaboration with Rogaland County Municipality.
Grønhaug was last excavated in 1902, when archaeologist Haakon Shetelig discovered the remains of a Viking Age ship burial. This time, researchers went deeper than Shetelig had and encountered evidence of an earlier structure beneath the Viking Age remains.
“We have received answers to the goal of this excavation, which was about the preservation conditions in the mound. In addition, several unexpected discoveries have been made, so we will find out much more than expected,” says Marie Ødegaard, associate professor of archaeology at the Archaeological Museum in Stavanger.
The results could shed new light not only on the Viking Age burial, but also on a landscape that had been associated with powerful elites for many centuries before the Vikings.
A Viking grave built over an older burial?
Grønhaug is located close to Reheia, one of Norway’s largest Bronze Age burial grounds. The mound measures about 30 metres across and four metres high and was constructed using bog soil and peat, with a core of pebbles surrounding the location of the ship.
Its position among much older monumental burials has long raised questions about whether Grønhaug itself originated before the Viking Age.
When Shetelig investigated the mound 124 years ago, he excavated only part of it. He later wanted to return to Grønhaug in 1926, in part because he suspected that the mound had originally been constructed during the Bronze Age. That second excavation never took place.
A century later, archaeologists may finally have found evidence supporting his theory.
“Considering the Bronze Age landscape that Grønhaug is part of, it is likely that this was also a Bronze Age mound. Among other things, we have found the outer edge of what may be a Bronze Age grave, which lies lower in the ground than the traces from the Viking Age. We would not have thought that it would be so obvious that a Viking grave had been built on top of the older existing grave,” says Ødegaard.
The discovery does not yet prove that the earlier remains date from the Bronze Age. Samples collected during the excavation will now undergo further examination and dating, a process expected to take several months.
If confirmed, however, the discovery would show that those responsible for the Viking Age ship burial deliberately placed their monument within a landscape that had already been associated with monumental burial and displays of power for many centuries.
The wider Reheia landscape reinforces that possibility. Seven monumental Bronze Age burial mounds survive there, forming some of the earliest prominent displays of power along the Karmsundet waterway.
The Grønhaug ship burial
The Viking Age burial at Grønhaug itself remains only partly understood. The oak ship found inside the mound measures approximately 15 metres long and 2.8 metres wide. The ship has been dated to around AD 864, although archaeologists believe the burial was created somewhat later.
“The Grønhaug shipwreck is interesting for many reasons,” says Håkon Reiersen, associate professor of archaeology at the Archaeological Museum, who is leading the investigation alongside Ødegaard. “Very little of this burial mound has been investigated. Dating the burial mound has been challenging. The ship dates to around the year 864, and the grave probably a little later, around the time Harald Fairhair took Avaldsnes into use as his royal seat. It has also been suggested that Grønhaug was Fairhair’s grave, but that is not the case.”
Avaldsnes, located nearby on Karmøy, became an important centre of royal power. Its location beside Karmsundet was particularly significant. The narrow waterway separates Karmøy from mainland Norway and formed an important maritime route along the country’s western coast.
The area’s archaeological remains indicate that control of this landscape had been important long before the Viking Age. Large and richly furnished burial mounds dating from the Bronze and Iron Ages demonstrate the presence of powerful elites around the waterway.
Grønhaug was also not the only ship burial constructed here. Nearby Storhaug contained another monumental ship burial, excavated in 1887. Recent research dates the Storhaug burial to AD 779, making it an early example of the monumental ship burial tradition that would later produce famous sites such as Oseberg and Gokstad.
Remarkable preservation inside the mound
Øyvind Nesvåg, Rogaland County Municipality
One of the principal aims of this month’s investigation was to determine how well archaeological material survives inside Grønhaug. Here, too, the results exceeded expectations.
The four archaeologists working at the site discovered birch bark, heather and pieces of wood believed to be more than 1,000 years old. Their survival indicates unusually favourable preservation conditions inside the mound.
Much of the ship itself also remains underground. The archaeologists deliberately placed their excavation trench several metres away from the surviving vessel, meaning that the new investigation did not involve reopening the ship burial itself.
That leaves open intriguing questions about what else might survive within Grønhaug.
“From other ship graves we know that, in addition to the ship itself, there were also small boats in some burial mounds,” says Reiersen. “There is actually a possibility that small boats may also be found here at Grønhaug,”
The possibility is not without precedent on Karmøy. The nineteenth-century excavation of nearby Storhaug uncovered both a ship and a smaller boat, along with weapons, tools and luxury objects. The 1902 excavation at Grønhaug also produced evidence of the wealth invested in the burial. Among the finds were exclusive down and textiles from elaborate carpets.
“It may be possible to find such things here. However, that was not the goal this time, because we do not have the budget for that. The excavation nevertheless shows that it is possible to find magnificent, royal objects if it becomes necessary to conduct a new archaeological investigation in the burial mound,” Reiersen adds.
For now, archaeologists are leaving those potential discoveries underground. The purpose of the excavation was to understand the mound’s construction and preservation rather than undertake a large-scale investigation of the Viking grave.
Grønhaug and Norway’s Viking heritage
The investigation also has a broader purpose. Norwegian heritage authorities are studying the country’s monumental Viking ship burial mounds as part of an effort that could eventually lead to a UNESCO World Heritage nomination.
In December 2025, Norway’s Directorate for Cultural Heritage recommended seven ship burial sites for inclusion on the country’s tentative list for World Heritage status.
The sites are Gjellestad in Østfold; Borrehaugene, Oseberghaugen and Gokstadhaugen in Vestfold; Storhaug in Rogaland; Myklebust in Vestland; and Herlaugshaugen in Trøndelag.
Storhaug’s inclusion makes the investigation of neighbouring Grønhaug particularly relevant, since researchers are increasingly considering these monuments as parts of wider cultural landscapes rather than simply as individual graves.
“The Viking Age is an important part of our history. The Viking ship graves are completely unique, and we believe they may have potential for a UNESCO nomination, and perhaps an inscription,” says National Heritage Commissioner Hanna Geiran.
The process remains at an early stage. Inclusion on Norway’s tentative list would not itself make the ship burial sites World Heritage Sites. The Norwegian government must first decide whether to proceed, after which a formal UNESCO nomination would require considerably more work.
“We are now carrying out an assignment on behalf of the Ministry of Climate and Environment for UNESCO’s tentative list. The government will decide whether we will proceed with the nomination. If that happens, it is an extensive process that will take time. But this excavation is an important step on the way,” says Geiran.
Norwegian heritage authorities argue that the monumental ship burials are important evidence for understanding Viking Age power, society and beliefs about death. The mounds themselves were enormous undertakings, requiring substantial resources and labour while creating highly visible monuments in the landscape.
At Karmøy, that landscape may now prove to have an even longer history than previously understood.
Waiting for the dates
The excavation at Grønhaug was completed after five days, but the archaeological investigation is far from finished. Researchers will spend the coming months examining the samples taken from the mound and attempting to establish more precise dates for its different layers.
Those results will be particularly important for determining whether the structure discovered beneath the Viking Age burial really does belong to the Bronze Age.
If it does, Grønhaug would preserve evidence of two very different periods of monumental burial at the same location: an earlier mound created within Karmøy’s Bronze Age landscape and a spectacular ship burial constructed there more than a thousand years later.
Before closing the excavation, the archaeologists added one more layer to Grønhaug’s long history. They left behind a letter addressed to archaeologists of the future, accompanied by a glass cup from Avaldsnes, several coins and a candle.
More than a century separated Shetelig’s investigation from the latest excavation. If Grønhaug is opened again far in the future, the next archaeologists to investigate the mound will find a small archaeological deposit left deliberately by their predecessors in 2026.
Top Image: Photo by Øyvind Nesvåg, Rogaland County Municipality
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