It is a jewel of 12the-century Romanesque architecture and one of the most curious and enigmatic monuments of Alto Aragon. Hidden among plants and perched on a hill just 2 kilometers form the village of Agüero, it remains a mystery.

The story behind its construction and the reason for its hurried completion are nuclear, with various theories existing. These hypotheses are further fueled by numerous small details, curiosities and signs found on the walls of this temple.