Beglik Tash is a natural phenomenon of huge megaliths arranged and carved by a Thracian tribe and later used for religious ceremonies. It is part of a wider surrounding area and a natural rock formation of huge monolithic blocks of volcanic origin, and were formed of hardened magma that erupted from a volcano active during the Mesozoic era. Currently, an open-air museum is maintained by the Burgas Historical Society. Most of the megaliths have traces of carvings for the purposes of Thracian rituals. There are also the remains of a labyrinth that visitors can pass through. A Thracian sun clock is formed from huge stones. There also is an enormously big rock, standing on only two points and a cave, resembling a woman's lap.