In the attic of the Main Building of the University there is a historical students' lock-up for confined students who had violated the public order and the rules of student behaviour.

Sentences involving detention in a lock up were passed by the University Court. Students serving their sentence amused themselves with drawing, writing verses or monograms on the walls, ceilings and doors. All methods were welcome, e. g. painting, scratching or scribbling. After the fire in 1965 the wall paintings were only partially restored. The caricatures and the texts of the lock-up are still amusing!