This monastery presents a unique feature: it is carved into natural rock. It's an ancient, rugged, almost primitive site that bears witness to the earliest hermit settlements in these lands. Due to its significant anthropological value, it was declared a historical artistic monument in 1923. The monastery's church, dating back to the 6th century, stands as one of the oldest known Christian temples. Its three naves are carved into the rock, and the ceiling of the central nave features an opening allowing light from the outside. A pillar serves as an altar. The church premises were expanded with a new nave in a later construction. The bell tower, a 15th-century work by Gonzalo de Penalva, is perched atop an enormous rock formation nearly 20 meters high, giving this place its name.