Ursuline Church of the Holy Trinity, Baroque parish church on Slovenska cesta, Ljubljana, Slovenia

The Ursuline Church of the Holy Trinity is a Baroque church on Slovenska cesta in Ljubljana, built between 1718 and 1726 to designs by Carlo Martinuzzi. Its east facade, facing Congress Square, has colossal three-quarter columns and a Borromini-inspired gable with three pointed niches. Inside, a barrel-vaulted hall with chapels and a domed presbytery holds Francesco Robba's marble altar of 1744.

The building was constructed between 1718 and 1726 under architect Carlo Martinuzzi, funded by merchant Jakob Schell von Schellenburg and his wife. This represented one of the city's major parish church projects during the Baroque period.

The church is dedicated to the Holy Trinity, not to Saint Ursula; its Slovenian name, uršulinska cerkev, refers to the Ursuline order that ran the adjoining monastery. The facade's three pointed niches likely allude to the Trinity. The main altar, carved by Francesco Robba in 1744, carries figures symbolising Faith, Hope and Charity.

Access to the interior is via a balustraded stairway added in 1930 at the main entrance, which connects the building to Congress Square. The church sits centrally on Slovenska cesta and is easily reached by public transportation.

Architect Jože Plečnik designed the 1930 stairway as part of a broader urban plan to reshape Congress Square. His intervention created a harmonious link between the historic church building and the modern public square.