The Dansker or the toilet tower of Torun Castle, Poland. This dansker was constructed in the 13th century by the Teutonic Knights over a creek (the stream of which floated away excreta of a castle garrison fallen through openings in a floor of the tower) as outer part of the castle, connected by an elevated passageway. The tower served not only for sanitary purposes but also for defense. This outer defensive structure concept was brought by the Teutonic Order from the Holy Land, probably borrowed from the Muslim builders as evolved version of the Barbican and Albarrana towers. The dansker could serve as a base for sallies or became a last refuge for castle defenders, where they can retreat, block the passage, and keep resisting. It is interesting that the same principle of blocking a narrow passageway to prevent unauthorized access is still used in important buildings (e.g. airports) these days