Holy Trinity Greek Orthodox Church, Greek Orthodox church in Innere Stadt, Vienna, Austria.

Holy Trinity Greek Orthodox Church is a red brick church on Fleischmarkt with a tower on its right side. The tower has an octagonal upper stage with narrow arched windows, a small round window above them, and a rounded dome with a cross. The lower facade has tall pointed arches framing windows and a recessed arched entrance, with short brick pinnacles along the roofline and stone trim outlining the arches.

Following Joseph II's Tolerance Patent of 1781, which allowed Greek Christians to worship openly, architect Peter Mollner built an initial structure here in 1787. The current building was later created by architect Theophil Hansen with support from diplomat Simon Sinas.

The parish was founded in 1787 under Joseph II's Patent of Toleration and served Habsburg subjects, while the nearby St. George's community represented Ottoman subjects. Since 1963 the church has been the cathedral of the Greek Orthodox Metropolis of Austria. The conductor Herbert von Karajan's family belonged to the parish.

The church stands at Fleischmarkt 13 in the Innere Stadt, its brick facade and green-domed tower facing the paved street directly. The entrance portal sits below the tower. Visitors should dress respectfully, since the building serves as the cathedral of the Greek Orthodox Metropolis of Austria and holds regular services.

The facade and vestibule frescoes were commissioned from Carl Rahl, while the frescoes inside the church are by Ludwig Thiersch. The church also kept a link to music: the family of conductor Herbert von Karajan belonged to the parish.