The Rock of the Three Kingdoms (Portuguese: Penedo dos Três Reinos), known also as Fragua dos Tres Reinos in Galicia, is a rocky formation of 1025 m of elevation in the Sierra del Marabón, part of the mountainous system of Sierra de la Culebra (Portuguese: Serra da Coroa), that was the former tripoint between the three ancient medieval kingdoms of Portugal, León, and Galicia, whence its name.