Artificial Caves of Alapraia

A Chalcolithic necropolis of four subterranean hypogea in Estoril, near Lisbon, created by excavating marlstone with stone tools during the 3rd millennium BC. The chambers measure 4.2-6.2 m in diameter with corridors up to 13.7 m long, featuring central skylights that classify them as coelheira-type caves. Burials placed along chamber walls included engraved black schist plaques worn as necklaces, carved stone sandal soles as votive objects, jewelry, and ceramics. The caves were used for over a thousand years.