The church adopts the Latin cross (symbol of Christianity), being composed of the main nave and the transept, where the tombs of D. Pedro and D. Inês de Castro are located.

The construction started by the head that consists of nine radiant chapels of trapezoidal plant, connected to each other and to the transept by a wanderer, being covered by vaults of cradles.

The lighting diffuses through the large rosette, the two lateral spans of the front, through the narrow cracks in the side walls and also through the rosettes and windows of the two tops of the transept and the high windows at the head.

The northern transept had direct access to the Dormitory of the Monks. At the opposite end of the transept, under a large rose window and two large windows, there is still the access door to the monks' cemetery, commonly known as the "Door of the Dead".