The Habsburgs' parish church, attached to the Hofburg. It was here that Maria Theresa married Franz Stephan of Lorraine in 1736 and where most subsequent Habsburg dynastic weddings took place — including Franz Joseph and Sisi in 1854. The Heart Crypt (Herzgruft) at the back holds 54 silver urns containing the embalmed hearts of Habsburg emperors and archdukes.
The high vault is Gothic, with Antonio Canova's marble pyramid tomb of Archduchess Marie Christine, daughter of Maria Theresa, set against one wall — one of the great neoclassical funerary monuments. Sunday morning High Mass with full orchestra and choir is exceptional.