[2][3] The original St. George chapel in the Leopoldsberg castle [de] was blown up during the first Turkish siege of Vienna [de],[4] Emperor Leopold I during the plague in Vienna[5] in 1679 had built on the Leopoldsberg (at the time still Kahlenberg) a new church dedicated to the Margrave Leopold III (of Babenbergs), who was canonized in 1485.

The church was furnished with important pieces of religious art, including a highly venerated depiction of St. Mary called "Maria Türkenhilfe".

[6] On February 7, 1945, an allied forces' bomb destroyed about a third of the church; among other things, the south tower was completely demolished.

[7] The reconstruction work that began soon afterwards reverted the church to its 1720 shape with the baroque towers instead of the classical ones built in 1824.

The central part of the church is designed in early baroque style with anteroom, diagonal side rooms and a surrounding gallery.

The towers are crowned with an entablature (that used to have a triglyph design), cornice and, at the top, an onion tin roof with a steeple ball and a cross.