This "Imperial Cathedral" was known as the "Royal Church of St. Mary at Aachen" during the Middle Ages. From 936 to 1531, the Aachen chapel was the church of coronation for 30 German kings and 12 queens.

In 792 Charlemagne began the construction of a palace here and part of the whole structure was this "Palatine Chapel". Pope Leo III consecrated the chappel in 805.

The carolingian octogon, having a baroque roof now, was planned by the Odo of Metz, who obviously had seen Byzantine churches. For sure he had had seen the Basilica of San Vitale of Ravenna, as San Vitale seems to be a model of this chapel.

The Palatine Chapel was a model for many buildings constructed later. One of these can be found in a small alsatian village of Ottmarsheim, about 500 kilometers southeast.

Having already uploaded many photos from previous visits, I will only add a few more of the interior.