Aachen, the westernmost city in Germany, developed from a Roman settlement and spa, subsequently becoming the preferred medieval Imperial residence of Emperor Charlemagne of the Frankish Empire. From 936 to 1531 Aachen was the place where 31 Holy Roman Emperors were crowned Kings of the Germans.

Pepin the Short had a castle residence built in the town, due to the proximity of the hot springs and also for strategic reasons between the Rhineland and northern France. Charlemagne´s coronation as king of the Franks took place here in 768. He spent most winters in Aachen between 792 and his death in 814. Aachen became the focus of his court and the political centre of his empire.

During the reign of Otto II, the nobles revolted and the West Franks under Lothair raided Aachen in 978. The palace and town of Aachen had fortifying walls built by order of Emperor Frederick Barbarossa between 1172 and 1176. Later Aachen remained a city of regional importance, due to its proximity to Flanders and achieved a modest position in the trade in woollen cloths, favoured by imperial privilege.

The "Hof" square, with its small cafés and restaurants (all closed during the lockdown), also contains this portico, a vestige of Aachen's Roman past. This was once a Roman bathing and temple district. Actually, this is a copy, as the original Roman arches are in the federal state museum in Bonn.