Theatre City or La Ciutat del Teatre is a cultural space integrated by three buildings: Teatre Lliure (the one you see in the image), Mercat de les Flors and the modern Theater Institute. If you remember my post titled Fountains at Montjuic: Passeig de Les Cascades in Barcelona from Sept 19th, this complex is located at carrer Lleida, near Paralelo avenue. The three emblematic buildings face Margarita Xirgu square which you can see in the photograph above.
As a result of the 1929 International Exhibition some buildings were built on the slope of Montjuic mountain, like the Palau de l’Agricultura, where Mercat de les Flors (see this other picture), and Teatre Lliure are. The Theater Institute is a relative new building dating from 2000, with a surface area of 20.000 sq. meters.