It is a cave on the southeastern side of Gellért Hill which gave the city half of its name. Seeing the hollow in the hill, and the other caves that underlie the Buda Hills, the Magyar conquerors from Asia - with no word of their own for cave - borrowed the Slavic word, "pest," from tribes living in the area.
They named what is now Gellért Hill "Pest Hill" - or hill of caves. In 1926 a lovely chapel, known as Rock Chapel, was built inside the hollow of Gellért Hill and can be visited today. The miles of caves under the city are the inactive vents of hot springs, the source of thermal water for all the city's spas. Sections of the labyrinthine cave system may be toured, for example Castle Cave at the corner of Országház and Dárda streets. Many caves have served as wine cellars and air raid shelters.