Granusturm Tower is the oldest extant buildings in Aachen and one of the oldest stone buildings in Germany. It was built in 788 as part of the royal palace of Charlemagne. Initially, Granusturm Tower in Aachen was 20 meters high. In the XIV century the town hall was built on the site of the destroyed palace of the emperor. They did not take down the tower, but smoothly incorporated into the architecture of the Town Hall. Along the way, another 14 meters were added to it.
The tower's name Granusturm clearly indicates the name of the ancient city - Aquisgranum. Granus was the Roman healing god. In those days, when the tower was erected, Latin was still used. In particular, Charlemagne himself used it. The purpose of the tower is still unclear. Many historians believe that it was inhabited and himself Charlemagne lived in it. The fact that the tower could serve as housing for Charles points to unprecedented luxury for the early Middle Ages. All three floors of the tower were heated, the warm air came along the walls of the fireplaces located at the bottom, as people did in the Roman Baths in ancient times. Moreover, the design of towers provided even toilets. Probably, Charlemagne was the only person in Western Europe of that time, who would need all of these amenities. Later, the tower nobody used as a living room. Starting from the XVI century, it housed the city archives of Aachen.