The Porta del Popolo on the north side of the Piazza marks one end, while the East is dominated by the passeggiata del Pincio. This piazza served as an exposition hall, a stadium, and a theater for popular plays. The face of the piazza changed a great deal from the 1400's to the 1800's, with the reconstruction of the Church of Santa Maria del Popolo, the placement of the Flaminian obelisk at the center of the piazza, and the addition of neo-classical elements by Giuseppe Valadier.