In 1571, following similar initiatives taken at several forts along the Portuguese coast, King Sebastian ordered the remodeling of the tower. At the time, the fort was named in honour of "São Brás" ("Saint Blaise"), the patron saint of artillerymen in the Portuguese tradition, and changed to honour the young King (lost at the Battle of Alcácer Quibir) and Saint Sebastian. Under the responsibility of Afonso Álvares, the new project transformed the fort into a massive fortress, becoming referred to as the "Fortress of São Sebastião da Caparica" (). Between 1580 and 1640 it was referred locally as the "Torre dos Castelhanos" ("Tower of the Castilians"), where it was remodeled structurally to meet the requirements of the Philippine Dynasty.