His tomb was first opened by the Emperor Otto III in the year 1000. According to contemporary chronicles, as Otto entered the underground chamber, he was struck by the vision of Charlemagne seated upon a throne, wearing a golden crown and holding a scepter, his fingernails sticking out the gloves.
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"He had not lost any of his members to decay, except only the tip of his nose. Emperor Otto replaced this with gold, took a tooth from Charles's mouth, walled up the entrance to the chamber and withdrew," the Chronicle of Novalesia, written about 1026, reported.
In 1165, Frederick I, also known as Barbarossa, re-opened the tomb, displayed the remains as holy relics, then buried Charles in a marble sarcophagus beneath the floor of the cathedral. Fifty years later, Frederick II re-interred him in a casket made of gold and silver.
In 1349, some of Charlemagne's bones were removed and kept as relics by Holy Roman Emperor Charles IV. After five undisturbed centuries, the founder of the Holy Roman Empire was exhumed again in 1861 for research purposes.