 The tunnels featured in this film are part of the Wienkanal, which  channels the Wien River through central Vienna out to the Danube  River. The main tunnel is the huge arched structure through which  the river flows a distance of about 1.6km. The gated side passages  are connections to a wet weather sewer overflow, and the chamber  with the balconies is the overflow point. The spiral staircase is  one of 6 exits from the main culvert. Tours are run through the  system on a daily basis. Events are occasionally held down the  tunnels in commemoration of the film and its characters.