Inside, the church has only one main area and a ribbed vault. The chancel is covered by a Gothic vault, with a carved gilt altarpiece and there are also excellent examples of sacred silverware.
The sacristy is panelled from floor to ceiling and contains beautiful paintings depicting scenes from the life of St. Inácio (the patron saint of the Jesuits). There are also two sculptures of this saint and St. Francis of Assisi.
The square, two-storey cloister is supported by columns.
This citadel is a notable example of a medieval fortification and contains the Domus Municipalis (Town Hall), the Santa Maria Church and the Pillory, together with a few dozen houses. It is one of the best combinations of city wall and citadel preserved in Portugal and is unique throughout the world. The wall has fifteen cubelos (cubic turrets) and three gates. One of the turrets is called the Torre da Princesa (Princess Tower) after a Moorish princess who fell in love with a Christian knight. After various vicissitudes, she was finally imprisoned in the tower (another variation on the Romeo and Juliet story, this time involving Moors and Christians who were bitter enemies at the time).
The 33 metre high keep stands in the centre of the group of buildings and is a perfect example of the Gothic military style, with its elegant embrasures in the upper wall, ogival windows and arrow slits. The building has three floors, the first containing a water tank, whilst the upper floor, with embrasures, overlooks a terrace and has four cylindrical sentry posts, one in each corner. And the view from up there? Stupendous! From the walls you can see the mountains and lands of Portugal and Spain, stretching as far as the eye can see.