Since the emergence of experimental and alternative theatre during the 1950s and 1960s, Eksperimentalno gledališče Glej (EG Glej), the Glej Theatre (Glej meaning 'Look!' - inspired by Richard Schechner, American avant-garde theatre theoretician), which was founded in 1970, has played an essential role in Slovene theatrical life. Besides being the first, Glej has also been the only theatre of its type to survive and today it is the oldest independent performing arts venue in Ljubljana.

Glej launched a new generation of authors, directors and actors, and an aesthetic that put Slovenia on the theatrical map through its success at international festivals some decades ago. Since the 70s EG Glej hosted several directors and groups of artists who were simultaneously developing a form of non-verbal, physical performing arts, and also experimenting with the more traditional dramatic form, eg Dušan Jovanović, Zvone Šedlbauer, Janez Pipan, Matjaž Zupančič, Eduard Miller, Nevenka Koprivšek, Bojan Jablanovec, Matjaž Pograjc, Tomaž Štrucl, Tomi Janežič, Sebastjan Horvat, Diego DeBrea, Jernej Lorenci, Ivana Djilas, etc.

Glej's small alternative space has also hosted numerous small-scale performances of theatre, comedy, mime, puppetry and multimedia work. Recently a cycle of drama readings called PreGlej in collaboration with the Integrali Cultural Association was introduced here, too.