Pilis Cave, Natural cave in Pilisszentkereszt, Hungary.

Pilis Cave is a natural cavity within the Pilis Mountains, carved through limestone rock with mineral deposits visible on its walls and ceiling. The underground passages reveal layers of stone shaped over millions of years by slow geological forces.

Foresters building a path found the entrance in autumn 1969. On 6 October 1970 the Diogenész group of the Vörös Meteor Természetbarát Egyesület surveyed the cave, then 150 m long, and drew a 1:400 plan. In 1972 members pushed a metre or two beyond the previous end point; in 1973 they could not get past it. The name Pilis-barlang first appears in print in 1976.

The cave's name appears in literature from 1976, when it was first called Pilis-barlang; earlier texts also used Pilis-tetői-barlang and Pilis-tetői cseppkőbarlang. Forestry workers building a path found the entrance in autumn 1969, and the Gábor Áron Cave Research Group made its first trip there that year. Cavers still enter only with permission from the Duna–Ipoly National Park Directorate.

Access requires special permits and professional guidance to protect the cave's natural formations from damage. Visitors should arrange their visit in advance and follow all preservation rules during their time inside.

The two entrances once worked as spring mouths, which is why the cave counts as an inactive spring cave. Inside, the walls of the nearly circular Nagy-kürtő shaft were polished smooth by descending karst water, and its top has not yet been climbed.