In Ancient Rome the area was unused space between Pompey's Theatre and the flood-prone Tiber. Though the Orsini established themselves on the south flank of the space in the 13th century, until the 15th century the square remained undeveloped. The first church in the immediate vicinity was built during the pontificate of Boniface IX (1389-1404), Santa Brigida a Campo dei Fiori; with the building-up of the rione, the church has now come to face that part of the former Campo that is now Piazza Farnese. In 1456 under Pope Callixtus III, Ludovico Cardinal Trevisani paved the area: this was part of a greater project of improvement of the rione Parione. This renewal was both the result and cause of several important buildings being built in the surroundings; in particular, the Orsini palace on Campo dei Fiori was rebuilt.