Mátyás-hegyi Cave

The Mátyás-hegy Cave, entered from Szépvölgyi Road in Budapest's second district, is part of the Pál-völgy cave system, which at roughly 32 kilometers ranks as the longest cave system in Hungary; a 5.3-kilometer passage links the Mátyás-hegy section to the main Pál-völgy cave. Unlike the developed show-cave route nearby, the Mátyás-hegy section has no paved walkway, and visits are run as adventure tours in which participants crawl and squeeze through undeveloped passages wearing overalls, helmets and headlamps supplied on site. The cave is notable for the marine fossils embedded in its walls — nummulites, bryozoans, foraminifera, sea-urchin fragments and mussel-shell remains — evidence that the rock formed under a sea that once covered the Buda hills tens of millions of years ago. Tours run year-round but must be booked in advance.