Church of San Tirso is the early 12th-century building and one of the oldest Mudejar churches in the province of Leon. It was one of the first Spanish Romanesque churches in the stone and monumental sculpture is replaced by brick to become what has come to be called Romanesque-Mudejar. The church is also an important stop on the Camino de Santiago.
The visit includes the museum and the monastery chapel, with the tombs of Alfonso VI and his wives. Silver highlights the custody of the sixteenth century, attributed to Enrique de Arfe and the Pilgrim Virgin of the sculptor Luisa Roldán.
The monastery has a small museum where works, mainly religious in character, from the former monastery (today desapareceido) of Benedictine monks and other Sahagun own or donations from organizations in the city funds are kept. The museum was founded in 1962 with the support of the then Bishop of Leon Mon. Almarcha . It consists of two rooms which are grouped more than two hundred works of art.