The well-known student prison in Heidelberg is located in the back alley of Heidelberg University Square. The student prison was built in 1712. Under the background of time and space at that time, the university students were prostitutes, alcoholics, troublemakers or idlers. The police could not shut them down. So the school set up "prison" and thought on the inner wall of the room with only beds, so the university students painted ducks on the walls to pass the time. So far, colorful and wild ducks are still seen filling every corner of the building.