The most important historical period of Aachen started with the takeover of the government by Charlemagne in 768 AD. The imperial palace, located next to the hot water springs, soon became Charlemagne’s permanent residence, and so developed into a spiritual and cultural center. As the economic development of Aachen proceeded, the town became more and more prosperous, and this has persisted to the present day. Charlemagne was buried in the Cathedral of Aachen in 814. (The Cathedral is Germany’s first UNESCO World Heritage site.) Two hundred years later he was canonized, which resulted in a flow of pilgrims wishing to visit and see Charlemagne’s tomb and the relics he gathered during his life. The relics are exhibited to the public every seven years. The Aachen Cathedral and its treasury are considered to be the principal ecclesiastical treasury north of the Alps. Aachen is now home to the Charlemagne Prize for politicians who advance European unity.