This church owes its fame to a miracle during the 1529 Ottoman siege. You're standing in front of a building where four men chained to a tree witnessed something that would draw pilgrims for centuries.
Ottoman forces were destroying Hietzing. Four locals had been chained to a tree right here. They'd hidden a wooden Mary statue inside that same tree before the attack. As they prayed, the statue began to glow. It spoke the words: Hüet's eng. Watch yourselves. Their chains shattered.
News spread across Austria. Pilgrims flooded in. This became one of the country's major pilgrimage destinations. Step inside and look at the high altar by Matthias Steinl from 1698. You'll see those four men with broken chains at Mary's feet, the statue positioned in a stylized tree crown.
The church had another devoted follower. Maria Theresia walked here every single day during her Schönbrunn stays. She had a special oratorium built where she could attend mass without being seen. She filled the church with gifts, including Stations of the Cross paintings from Schönbrunn Palace.
The building dates mostly from 1685, rebuilt after the second Ottoman siege destroyed it. The neo-Gothic facade and tower you see came in the 1860s. The saint statues on the front were carved by Andreas Halbig and Johann Meixner in 1865.
Sources. Story: https://www.geschichtewiki.wien.gv.at/Hietzinger_Kirche, https://en.wikipedia.org/wiki/Maria_Hietzing_Parish_Church Photos: Welleschik, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons
