The Monastery of Santo Toribio de Liébana is a Roman Catholic monastery located in the district of Liébana, near Potes. The monastery is one of the five places of Christianity that, together with Rome, Jerusalem, Santiago de Compostela and Caravaca de la Cruz, has the privilege of perpetual indulgences.

The monastery was founded prior to the 6th century. According to tradition, the monastery venerates that largest piece of the Lignum Crucis discovered in Jerusalem by Saint Helena of Constantinople. Brought from the Church of the Holy Sepulcher by Saint Turibius of Astorga, the left arm of the True Cross is kept on a gilded silver reliquary. The monastery was initially dedicated to St. Martin of Tours but its name was changed in the 12th century.

On April 16, 1961, the Franciscan friars, Custodians of the Holy Places, were entrusted with the relic's safekeeping and with the promotion of the devotion to the Holy Cross.