The architecture and the decoration are in the Italian Baroque style. It presents some novel solutions to problems that the scenic tradition had not yet been able to solve.
The axis of the room, that is in shape of a horseshoe, is oriented perpendicularly to the stage, right under the “prince’s gaze”. As in the Lisbon Coliseum and in the São Carlos Theatre, the most important place is situated in front of the stage, under the arches shaped like a horseshoe, of Arab inspiration. From there, the room is organized on a hierarchical scale: the theatre boxes on the main floor and the upper boxes, of the 1st and the 2nd order (for the wealthy classes), and in the stalls sat the middle class. The galleries up above were reserved for the poorer classes. The latter did not enter through the main theatre door, but by side entrances that still exist today and which are now used for trade and other services.
The Italianate theatre is also a space organized to see and to be seen : the theatre boxes are like small rooms where one can “entertain guests”. Eça de Queirós described it perfectly in his novel "Os Maias".
The stalls were built on a slant and so was the stage. This allows the performer’s full body to be seen, an ideal solution and an innovation at the time.