"Peterskirche (St. Peter's Church), Vienna" by Axe.Man on Flickr - St. Peter's Church is thought to occupy the oldest Christian sacred site in Vienna, as a church has stood here since the second half of the 4th century. According to legend, Charlemagne founded a larger church here in 792. The present St. Peter's Church was constructed by Gabriel Montani from 1702 to 1708. Hildebrandt, the noted architect of the Belvedere Palace, finished the building in 1732.