With its rugged fortress-church appearance, the cathedral of Porto, built in the 12C, is one of the first important Romanesque in Portugal. It underwent profound modifications in the 17C and 18C. The chapel of the Holy Sacrament, which opens off the left arm of the transept, has a very attractive altar with a sculpted silver retable. The adjoining cloister, which dates from the 14C, is completely covered with panels of azulejos made by Valentim de Almeida between 1729 and 1731.