Budapest is the capital of caves. It is the only capital in the world which has caves of significant size and length underneath its buildings and streets. More than two hundred caves are known under the Buda side of the town. However these caves also have a special place in the world because of their unusual thermal water based development.
The hydrothermal caves of Budapest were created by the same thermal springs that supply the famous spas of the capital and the entire area is on the tentative list of UNESCO World Heritage Sites.