The layout of the piazza today was designed in neoclassical style between 1811 and 1822 by the architect Giuseppe Valadier,[1] He removed a modest fountain by Giacomo Della Porta, erected in 1572,[2] and demolished some insignificant buildings and haphazard high screening walls to form two semicircles, reminiscent of Bernini's plan for St. Peter's Square, replacing the original cramped trapezoidal square centred on the Via Flaminia.

Valadier's Piazza del Popolo, however, incorporated the verdure of trees as an essential element; he conceived his space in a third dimension, expressed in the building of the viale that leads up to the balustraded overlook from the Pincio (above, right).

Close scrutiny of the twin churches reveals that they are not mere copies of one another, as they would have been in a Neoclassical project, but vary in their details, offering variety within their symmetrical balance in Baroque fashion.

The gateway was reworked to give its current appearance by Bernini for Pope Alexander VII in 1655, to welcome Queen Christina of Sweden to Rome following her conversion to Roman Catholicism and her abdication.

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.

[6] At the center of the piazza is the Fontana dell' Obelisco: a group of four mini fountains, each comprising a lion on a stepped plinth, surround the obelisk.