Mariastern Abbey, Trappist monastery in Delibašino Selo, Banja Luka, Bosnia and Herzegovina

Mariastern Abbey is a Trappist monastery in Delibašino Selo featuring a church dedicated to the Assumption of Mary and residential buildings for monks. The grounds sit near the Vrbas River and include structures that developed over more than a century.

Franz Pfanner bought 100 acres at Delibašino Selo on 10 June 1869 for 1,400 ducats, and the Trappists arrived on 21 June, the founding date. The monastery was raised to an abbey by a Rescript of 4 December 1885, with Bonaventure Bayer appointed first abbot on 27 January 1886. By the early 20th century it counted 219 monks, the largest Trappist abbey in the world; it was closed in 2017.

The abbey's Croatian name, Marija Zvijezda, means Mary Star. The Trappists followed the rule ora et labora, and their cultural imprint included a brewery, the first private hydroelectric plant in the area, and the Trapist cheese. After the 2017 closure, two monks remained, making it the smallest Trappist community in the world.

The abbey closed in 2017, so there are no monks, no shop and no prayer times to plan around. The monastic church of the Dormition of the Blessed Virgin Mary, declared a National Monument in 2004, stands in Delibašino Selo beside the Vrbas River, a short trip from central Banja Luka. Check access to the church before setting out, since the complex is no longer a working monastery.

The monastery had electric lighting by 1899, well before the city of Banja Luka received widespread power connections. This early adoption shows how forward-thinking the monastic community was at the time.