Pustý Zámek, Extinct volcano in Hradiště Military Area, Czech Republic.

Pustý Zámek is an extinct volcano in the Doupov Mountains with steep rocky slopes rising to approximately 933 meters (3,060 feet). The mountain's shape comes from ancient lava flows and volcanic structures that remain visible in its terrain.

The volcano formed during the Tertiary period through volcanic activity that created the rock formations visible today. In 1953, the area became a military training ground after the nearby settlement of Doupov was evacuated, restricting public access for decades.

The name Pustý zámek, German Ödschloßberg, means "deserted castle mountain", though no castle ever stood here. The summit lies in the Hradiště military training area, closed to the public, so the place is known only from maps and literature. Its old beech forests were partly replaced by spruce plantations.

The summit lies in the central part of the Hradiště military training area, about ten kilometres northeast of Bochov in the Karlovy Vary district, and is closed to the public. There is no marked trail or permitted route to the top; the mountain can only be viewed from outside the military area.

The summit's rocky outcrops contain cylindrical cavities about one metre deep, formed by gas eruptions in the lava; some authors instead attribute them to holes left by rotted tree trunks. The mountain is closed to the public inside the Hradiště military area.