The monumental cloister in the Doric-Roman style; 22 meters side. One of the notable pieces of the building, where solidity, elegance and sobriety are happily linked. Its meter and a half thick pilasters support a simple entablature, with a frieze decorated with triglyphs and metopes. Surrounding the courtyard is an open cloister, 33 m long, 4 m wide and 6.5 m high, covered with a groined vault and rose windows at the intersections of the ribs. In the middle of each side and at the top there are four beautifully carved stone shields: that of Cardinal Rodrigo de Castro, Casa de Lemos, Casa de Alba and that of Escuelas Pías. The latter appears among the others, because it was the Piarists who finished the works, which were incomplete, between the years 1919-1926. (Northeast and northwest corridors. You can see the new stone).
A closed gallery forms the upper floor of the cloister.