The original plan was conceived by Girolamo Rainaldi, continued by his son, Carlo Rainaldi, and completed, especially the facade and towers, by Borromini. "The church must be regarded as the High Baroque revision of the centralized plan for St. Peter's. The dome of St. Agnese has a distinct place in a long line of domes dependent on Michelangelo's creation - here dome and towers form a grand unit, perfectly balanced in scale. Never before had it been possible for a beholder to view at a glance such a rich and varied group of towers and dome - here the spatial reversal of the facade of S. Ivo is repeated." (p. 142) The site is where Saint Agnes was martyred in the Circus of Domitian, now the Piazza Navona.