Aachen, Charlemagne’s favored residence, is in modern Germany. The city lies in North Rhine-Westphalia near the borders with Belgium and the Netherlands, a location that made it a useful center for governing the Frankish realm.
Charlemagne inherited an itinerant royal court, but Aachen became increasingly important during his reign. Its position in Austrasia connected it with the Carolingian family’s heartlands and placed it close to the Saxon frontier. The area also offered forests for hunting and famous hot springs inherited from the Roman settlement known as Aquae Granni.
From the 790s, Charlemagne invested heavily in a permanent palace complex. Its best-known surviving building is the Palatine Chapel, begun under the architect Odo of Metz and later incorporated into Aachen Cathedral. The palace helped transform Aachen from a regional residence into the political and ceremonial heart of the empire.
Charlemagne spent much of his later life there and rarely traveled after about 807. A common mix-up is to place Aachen in France because Charlemagne ruled the Franks; modern borders are different from the medieval kingdom, and Aachen is firmly in present-day Germany.