Aachen is in Western Germany, near the border with the Netherlands and Belgium. Charles the Great, King of the Franks, began the construction of his palace chapel in the late 8th century. He commissioned the construction of Aachen Cathedral, which features an octagonal dome 32 meters high. His tomb is in the Cathedral altar. It is adorned with engravings of the King and Pope Leo the Third. Pope Leo crowned Charlemagne as the Imperator Romanorum, Emperor of the Romans, in the year 800.
The great dome above the altar is octagonal because Charlemagne placed special significance on the number “eight”. The numeral appears frequently in the Holy Bible, it was charged with symbolism in the Christian world during medieval times. An octagon can be made by drawing two intersecting squares within a circle. The circle represents God’s eternity while the square represents the secular world. The four corners also represent the four directions to heaven and the four characteristics of man. Charlemagne saw the number eight as symbolising the power of the Franks and the Roman Empire, the ruler of both the secular and religious worlds.
The Franks were later to become known as the Holy Roman Empire. The Emperor’s throne built in the 10th century overlooks the altar. The two relics in his hands were symbols of his power as ruler of two worlds. Charlemagne is holding a sceptre symbolizing his rule of the secular world in his right hand, while in his left he holds an orb, the symbol of the religious world.