Holy Trinity Greek Orthodox Church in located in the historic Greek neighborhood of Vienna's Innere Stadt. Greek Orthodox churches have existed near this site since 1787, as a result of the 1781 Patent of Toleration issued by Joseph II, Holy Roman Emperor. The architect of the 1787 building was Peter Mollner.
The current building is a Byzantine Revival re-design of the Mollner building by Danish-Austrian neo-classic architect Theophil Hansen. Greek-Austrian diplomat and philanthropist Simon Sinas funded the project, one of many collaborations with Hansen in Vienna and Athens. The cathedral was inaugurated on December 21, 1858.
The exterior features two-tone brickwork and gilded archways. The elaborately ornamented sanctuary shows a stylish allusion to Baroque church architecture typical of southern Germany and Austria. A number of frescoes for the facade and vestibule were commissioned from the Austrian painter and art professor Carl Rahl, with other frescoes by Ludwig Thiersch.
Since 1963 the cathedral has been the seat of the Greek Orthodox Metropolis of Austria.
References:The Church of St Donatus name refers to Donatus of Zadar, who began construction on this church in the 9th century and ended it on the northeastern part of the Roman forum. It is the largest Pre-Romanesque building in Croatia.
The beginning of the building of the church was placed to the second half of the 8th century, and it is supposed to have been completed in the 9th century. The Zadar bishop and diplomat Donat (8th and 9th centuries) is credited with the building of the church. He led the representations of the Dalmatian cities to Constantinople and Charles the Great, which is why this church bears slight resemblance to Charlemagne's court chapels, especially the one in Aachen, and also to the Basilica of San Vitale in Ravenna. It belongs to the Pre-Romanesque architectural period.
The circular church, formerly domed, is 27 m high and is characterised by simplicity and technical primitivism.