The Narrenturm is a round five-storey block of identical cells, twenty-eight to a floor, and the first building in Europe put up specifically to hold the mentally ill. The plan carries the whole idea: each floor is one ring corridor, the cells are all the same size, and each had its own drain. The reform stopped at the cell door. Chains stayed in use for decades, and by the 1820s the building was already called unfit.
It opened in 1784, paid for by Joseph II out of his own fortune and set beside his new General Hospital, because he wanted the state rather than the monasteries to look after the sick poor. Patients left in the 1860s, and since 1971 the tower has held a medical collection of diseased organs and tissue, close to fifty thousand objects. The ground-floor cells are the exhibition rooms, so you walk the same ring, and each old cell holds one subject: inflammation, tuberculosis, tumours, then one organ system at a time. Most of what is in the glass cylinders is human.