The Gellért Hill Cave (Hungarian: Gellérthegyi-barlang) is part of a network of caves within Gellért Hill in Budapest, Hungary. The cave is also referred to as "Saint Ivan's Cave" (Szent Iván-barlang), 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 ("Muddy Baths"), now called Gellért Baths.