Wotruba Church, Brutalist church in Mauer, Austria

The Church of the Most Holy Trinity comprises 152 massive concrete blocks of varying dimensions arranged asymmetrically on a hillside in southern Vienna. Narrow gaps between blocks accommodate glass panels that channel natural light into the interior spaces. The structure rises in stepped formation toward its peak, resembling an abstract concrete sculpture. Interior spaces open upward with varying ceiling heights determined by the positioning of surrounding blocks.

Margarethe Ottillinger, abducted to the Soviet Union in 1948, initiated the church on the site of a World War II Luftnachrichtentruppen barracks. Fritz Wotruba designed it; after his death in 1975, architect Fritz Gerhard Mayr oversaw completion in October 1976. A 2018/2019 addition provides barrier-free access to the upper and lower churches.

This Catholic parish church serves both liturgical needs and attracts architecture enthusiasts who study its unconventional design language. Since the 1970s, the building has functioned as a meeting point for those interested in modern sacred spaces. The design sparked heated debate when first revealed but has gained recognition as an important contribution to contemporary ecclesiastical architecture within Austria and internationally.

The church stands at 328 m above sea level on the northern slope of the Georgenberg at Ottillingerplatz 1, in Mauer, the westernmost part of Vienna's 23rd district. A 2018/2019 annex provides barrier-free access to the upper and lower churches. Just south of the building lies the Sterngarten of the Austrian astronomy association, an open-air planetarium platform with three tall masts used for guided sky tours. The building measures 30 meters in length and 22 meters in width.

The 152 blocks range from 0.84 m³ (1.84 t) to 64 m³ (141 t), and the tallest block stands 13.10 m high. The altar wall holds a cast of the crucifix Wotruba made for the Hofkirche in Bruchsal, Germany. The lower floor contains a parish hall of almost 350 m².