The first two Kings of Portugal are buried here. The tomb of Dom Afonso Henriques (1110-1185), the first King of Portugal, is on the left of the mausoleum. The tomb of Dom Sancho I (1154-1211), son and heir to the throne of King Afonso, is located on the opposite side.

Although the layout of the tombs is of gothic nature, the decoration contains Renaissance and Manueline characteristics. The project is attributed to Diogo de Castilho.

The sculptures that make up the tomb of Dom Afonso Henriques include Our Lady of the Assumption in the centre surrounded by musician angels, two evangelists on the bottom and two prophets at the top, the national coat of arms, and St. Christopher and St. Helena. In addition, there are twelve apostles in the side pillars.

The sculptures that make up the tomb of Dom Sancho I include the The Virgin and Child in the middle, sided by two saints called St. Catarina and St. Maria Magdalena, the Four Great Doctors of the Western Church, the representation of three theological virtues in the outer parts, the figure of an unidentified bishop and the national coat of arms. The pillars hold representations of the four cardinal virtues: justice, prudence, temperance, and fortitude.