Casa do Penedo is an architectural monument located between Celorico de Basto and Fafe, in northern Portugal. It received its name because it was built from four large boulders that serve as the foundation, walls and ceiling of the house. Its construction began in 1972 and lasted about two years. The residence was initially used by the owners as a holiday destination. Today, Casa de Penedo is a small museum of relics and photographs from Penedo’s history. Due to its unusual design and integration into the surrounding nature, the building has become a growing tourist attraction/
info source: wikipedia
By Pablo García Chao – Own work, CC BY-SA 3.0, Link