The Basilica occupies the central part of the building, flanked by bell towers and has the first dome (octagonal) built in Portugal. It was conceived by the German João Frederico Ludovice, a goldsmith and military engineering officer who had lived in Rome. Of particular note is the statuary commanded by the King to Italian masters, which constitutes the most significant collection of Italian Baroque sculpture outside Italy, the marble altarpieces of the altars, by the Mafra School of Sculpture directed by Alessandro Giusti and the set of six historical organs, unique in the world.