During Nazi occupation in World War II, a series of tunnels were built underneath the Gornji Grad neighborhood of central Zagreb to act as public air raid shelters. Today, the tunnels have been renovated and now offer a quick and safe way for pedestrians to cross part of the city without having to climb the hill through which they were constructed. The tunnels, despite being rather narrow, are also home to a Christmas market and and various cultural events.
For the technically inclined...