In his urbanistic project, Valadier constructed the matching palazzi that provide a frame for the scenography of the twin churches and hold down two corners of his composition. He positioned a third palazzo to face these and matched a low structure screening the flank of Santa Maria del Popolo, with its fine Early Renaissance façade, together holding down the two northern corners. Valadier outlined this newly defined oval forecourt to the city of Rome with identical sweeps of wall, forming curving exedra-like spaces.