In mid 16th century the monastery of São Salvador, in Grijó (Southwest of the city of Gaia) was in ruins and King João III authorized its transfer to São Nicolau de Vila Nova (Saint Nicholas Hill), across the river from Porto (later known as Serra do Pilar). Hence, in 1537, a new monastery was built on this hill, in honour of São Salvador do Mundo. It was designed by Diogo de Castilho and João de Ruão, and constructed under the command of Fryer Brás de Barros. By 1542, the first phase of its construction was finished and the priests from Grijó already occupied the building. The monastery includes the church with a circular central body and a rectangular main chapel (capela-mor) and a circular cloister, all in a continuum.
During Napoleon first invasion of Portugal, in 1809, the monastery was occupied by Wellington troops, to prepare the attack of the Portuguese troops to Porto, at the time occupied by the French army. Later, during the city siege, between 1832 and 1833, it was the only spot outside the city that the Liberal army managed to maintain, to help the sieged population of the city. Once the war ended, the building had to be rebuilt, given its poor state of preservation, created by the constant attacks it sustained.
Today, the Monastery of Serra do Pilar is part of the Oporto and Gaia Historic Centre, listed by UNESCO as a World Heritage Site.