The Gellért Hill Cave is part of a network of caves within Gellért Hill in Budapest, Hungary. The cave is also referred to as "Saint Ivan's Cave", regarding a hermit who lived there and is believed to have used the natural thermal water of a muddy lake next to the cave to heal the sick. It is likely that this same water fed the pools of the old Sáros fürdő, now called Gellért Baths.