The Križanke open-air theatre can host 3,500 spectators and holds 1,360 seats. The southern courtyard has proved to be a superb venue for classical, jazz, and rock concerts. The Križanke Church also sometimes serves as an occasional exhibition and concert venue.
Construction of the original Monastery of the Order of Teutonic Knights at Križanke is believed to have commenced in 1228. The earthquake of 1511 severely damaged the monastery buildings and they were partly rebuilt 50 years later. The original church was completely rebuilt in Baroque style between 1714 and 1715; it was designed by Venetian architect Domenico Rossi in a shape of a Greek cross, and was the first church of its kind in Slovenia. It has an ornate exterior and the gate area is accentuated with pilasters and a typical undulating dome. Slovene masters participated in the building process, including Gregor Maček, who designed the present-day City Hall. The City Museum of Ljubljana keeps the original model of this church. The Knight's Hall was also built during the 18th century.
Križanke continued to serve as a monastery until 1945, when the complex was nationalised. In 1952 representatives of the city of Ljubljana asked the architect Jože Plečnik to remodel the now derelict monastery into a venue for Ljubljana Festival. Jože Plečnik's last great contribution to the city at the impressive age of eighty (the works were completed in 1956) transformed the abandoned monastery into an open-air theatre and festival space.
Plečnik paved the main courtyard and added arcades shaped as theatre boxes to the facade. In the renovation process Plečnik collected and reused old statues and portals of the houses which were being demolished around Ljubljana. Inside the building, he designed a restaurant, using a number of Semperian elements (including coloured sgraffiti decoration outside, above the shallow archways). The so-called Infernal Courtyard is a distinct Mediterranean space with a grid of wall lanterns, intended for musical performances.
The redesigned court was not appropriate for live performances of a bigger scale, therefore the new open-air theatre was arranged in the former monastery garden. After Plečnik's death, his assistant Anton Bitenc continued the work.