The design for the National Theatre of Catalonia follows the architectonic tradition of the Greek theatre. The building combines two classic archetypes: the temple and the hemicycle.

The need for a set-building workshop, rehearsal room, a space for avant-garde theatre and other facilities prompted the construction of two separate buildings. The main building contains the 1000-seater main hall, classical in treatment, and a smaller 400-seater hall for experimental and avant-garde theatre.

Entirely glazed, the main façade of the National Theatre of Catalonia features a flight of steps for access than can be used as impromptu seating for open-air performances in the new Plaza de les Arts.

The main building is composed of three spaces: a spacious entrance hall, the seating area for the audience and the stage and its services.  The three spaces form a single volume under a metal and glass pitched roof with a 50 m span supported on two colonnades of architectural concrete. The glazed walls allow a view of the exterior from inside the plant-filled vestibule, which houses the restaurants.

The experimental theatre is on the lower floor. The area which accommodates the spectators forms a unitary volume within the great of the vestibule, like one building inside another. It has a pronounced slope for improved visibility, with the entrance in the upper part.