The theatre opened its doors on 27 August 1667 under the name Casa de las Comedias (House of Comedies) and with a capacity of 800 people. A board of theologians had gathered beforehand in order to determine if it was legal to stage comedies.
This Casa de las Comedias had a basically rectangular shape floor plan, over three floors and four floors of boxes, with an auditorium and stage. It had a lobby, a café, corridors, stairs to access the different levels and some storage rooms. It followed the model of corrales (Spanish open-air theatres) thus eschewing the curved shape adopted in a large part of Europe. In 1788 an arched gateway was created in the facade, with a terrace located over it.
The last work on the Teatre Principal began in 2002 and the architect Felipe Delgado Laguna was commissioned to carry it out. The project, completed in 2007, was based around the idea of adapting the building to current needs by fitting it out with the latest technological advances.
The extension has resulted in an exterior metal body, that is totally neutral and inside the height of the stage has been extended from 14 to 23 metres. The restored theatre has retained its historic character.