This photo, taken from the dome of Saint Peter's, shows the size and shape of Saint Peter's square. Built in 1667 and designed by Bernini, the square is enclosed by a grand collonade that consists of three aisles between four rows of columns. By a trick of visual perspective, a tourist standing on a stone marker near the Egyptian obelisk sees only one row of columns -- the other three rows line up perfectly behind the front column. The square can easily hold over 400,000 people. The broad street leading from the square, the Via della Conciliazione, was built by Mussolini in the 1930's and leads to a bridge across the Tiber River.