One of the oldest churches in Vienna (800 years old) and one of the few Romanesque buildings is St. Michael's across from the Hofburg Palace. Dedicated to the Archangel Michael, it was the original parish church for the Imperial Court. It has remained unchanged since 1792. The main altar, known as "The Fall of Angels" with a cloud burst of angels and cherubs, was designed in 1782 by Jean-Baptise d'Avrange. The church's pipe organ, the largest baroque organ in Vienna, was designed in 1714 by Johann David Sieber. It was once played by 17 year old Joseph Haydn in 1749. Mozart's " Requiem" was first performed here in 1791.
The crypt, "Michaelergruff", under the church is where many rich and noble folks bought space for burial. Originally, the coffins were lowered into the crypt through marble slabs in the church proper. As the crypt began to fill up, the smell overwhelmed parishioners so much that a stairwell was built off to the side and from that point on coffins went into the crypt that way. There were over 4000 corpses buried here. Because of the dry conditions in the crypt, several bodies became mummified. Among the corpses is Pietro Metastano (1698-1782) one of the most famous opera libretto composers in Vienna. Just in front of the main entrance to St. Michael's are the remains of the settlement of Canobae (for military wives and children) which was part of the Roman Army camp of Vindobona.