The large interior has three naves, the central nave being covered by a barrel vault. The side vaults are lower and the semicircular arches are supported by numerous columns. At the top stands the chancel with a wooden altarpiece and two other chapels. There are also other chapels and tombs of important figures from the Middle Ages.
The cloister is a later, Gothic, addition and consists of a series of five-pointed arches encompassing twin rounded arches crowned with an eye window. Despite the Gothic style, the cloister retains an air of Romanesque simplicity.
An important centre of learning and study during the Middle Ages, this church stands in the lower part of Coimbra, between old buildings. It is a medieval building but was significantly altered during the reign of King Manuel at the time of the Discoveries. A Baroque triumphal arch was also added in the 18th. century, extending the façade as if to encourage passers-by to enter. Behind this, there is a lavishly decorated Manueline porch. The building is therefore a mixture of various styles, a typical feature of buildings that are close to one thousand years old, although nothing has been preserved of the original Romanesque architecture.
The interior is spacious and has only one nave. By the entrance, it is worth taking a closer look at the choir stalls, a marvellous 16th. century work. Passing beneath the choir, there is a fine baroque organ. The interior is covered by a Manueline stellar vault and the magnificent and elaborately decorated tombs are from the same period. The nave also includes a Renaissance pulpit. The whole is a living lesson in ancient Portuguese art. There is also a chapter house and sacristy.Together with the Santa Engrácia church in Lisbon, it is considered a National Pantheon since it contains the tombs of the first two kings of Portugal (King. Afonso Henriques and King D. Sancho I).
Inside, the gilded wooden shelves, painted ceilings and inlaid floors are unique in the country. The spines of the books line the walls like exotic tapestries.