Crenellations: Crowning Castles

By Danielle Trynoski

Crenellations are one of the most recognizable elements of a medieval castle. These upright projections resemble teeth, bared at invaders to prevent their attempted entries and at allies to show the owner’s strength.

Each upright section is called a merlon or crenel, and they protected defenders from attacks. Defenses could be further increased by the addition of shutters or doors over the gaps (embrasures) as recreated at Gravensteen in Gent, Belgium. Crenellations were just one element in the line of defense. They would frequently be paired with arrow slits, machicolations, brattices, or hourdings. Despite being used in the Middle Ages, some merlons are modern imitations. Merlons were frequently added to buildings in a fit of 18th and 19th century Romantic imitative construction.


In the Valle d’Aosta of northern Italy, the merlons make a unique fishtail shape similar to the Ghibelline style. The Ghibelline style is a swallow-tail projection with a forked top. You can see these fishtail merlons at multiple castles, including Fénis Castle. Its double curtain walls and medieval frescoes reflect its history as a high-status fortified residence, yet it was restored in the 19th century. At Saint-Pierre Castle, owned by the de Sancto Petro (“Saint-Pierre”) family, it was first mentioned in documents from 1191. The castle was renovated by subsequent owners in the 17th century (the Roncas family) and the 19th century (the Baron Emanuele Bollati). Bollati was swept up in the Romantic movement and added battlements and the four small towers topping the corners of the central keep. So which family added the fishtails? At La Tour de l’Archet Morgex near Courmayeur, the earliest part of the current structure dates from the 10-11th century, and the complex was expanded in the 12-13th centuries.

Aside from the fishtail merlons, the Guelph style are rectangular merlons with flat or pointed tops. Cly Castle near Saint-Denis in Aosta includes an 11th century donjon and chapel, with extensions added in 1376 and 1550. Its crenellations are pointed, perhaps to add to the overall defensive aesthetic of the structure. The variations in shape are especially noticeable when multiple styles are extant at one site such as at Aymanvilles Castle.

Aymanvilles Castle, Aosta. Two of the towers with Ghibelline merlons, and two towers with Guelph merlons. Image:

Originally from 12th century, then enfeoffed in 1354 to Aimone de Challant. Its four round towers were likely built in the late 14th century by his son Amedeo, with two pairs of defensive motifs used in the towers’ construction. It was further renovated in 18th century by Joseph-Félix of Challant, who added the palatial fronts between the towers.

The west facade of Coimbra Cathedral, Coimbra, Portugal. Photo: Wikicommons.

There are a few surviving churches with crenellations. These fortified church castles exist in regions which were commonly disputed by political or religious factions in the Middle Ages such as Turkey, Portugal, the United Kingdom, and especially Romania. The Transylvania region of Romania is a UNESCO World Heritage Site, containing over 150 well-preserved fortified churches constructed between 1200-1500. Many of these structures share features with castles including curtain walls, towers, and crenellations.

With the increasing use of cannons and heavier artillery in the 15th century, defensive structures changed in response to these new bombardments. While the pot-de-fer was in use as early as the 1200’s, widespread use of cannon by the 1500’s lowered the use of archers behind castle merlons. Castle walls became thicker and changed shape, eventually developing the star fort shape in the 16th century. Crenellations went out of fashion for a few centuries, then were revived in the 19th century to imitate medieval buildings and to “restore” existing structures. While crenellations were a significant part of medieval defensive structures, don’t always assume that their presence signals a medieval building. Those merlons might be crowning a modern fantasy, or a mighty medieval castle.

Additional Reading:

The Ordnance Survey Guide to Castles in Britain, Peter Furtado

Official Tourism Site for the Valle d’Aosta

The medieval fortified church of Aita Mare in Romania. Photo: Wikicommons

Danielle Trynoski is the West Coast correspondent for and is the co-editor of The Medieval Magazine.


Top Image: Fénis Castle, Aosta. Note the elaborate use of Ghibelline style merlons in the crenellations. Photo: Wikicommons.