Granus Tower, Aachen

The Granusturm is a monument in Aachen and was originally built as part of Charlemagne 's imperial palace. The roughly 20 meter high tower, made of quarry stone, was completed in AD 788. The sides of the square building measure 8.85 meters. Today, the Granusturm is one of Aachen 's two town hall towers, along with the Marktturm. According to the current state of research, it was named after the Celtic god of healing Grannus (cf. also Aquae Granni ).

There is a vaulted room on each of three floors. Stairs between the interior walls and the exterior masonry connect the floors. A water-flushed latrine was installed in a vaulted room on the ground floor.

The function of the tower is so far unclear and is currently the subject of research. Previous assumptions that the building temporarily served as a residential tower for Charlemagne's family seem to have no substance. The building could not be heated, there were no sanitary facilities on the upper floors and the lighting conditions are insufficient, since the only small windows were covered with thinly scraped and greased animal skins in iron window frames to protect against rain or snow during the cold season.

The tower is currently assigned the function of a stairwell. This made it possible to climb to the upper floor of the porch of the King's Hall and thus the transition to an adjacent (late antique) fortification wall that ran in a circle around the market hill, and thus to possible other buildings attached to this ring wall. Corridors lead into the basement of the tower, some of which are now buried and walled up.