Caravaggio's celebrated Madonna of the Pilgrims—which scandalized all of Rome because a kneeling pilgrim is pictured, all too realistically for the era's tastes, with dirt on the soles of his feet, with the Madonna standing in a less than majestic pose in a dilapidated doorway—is in the first chapel on the left. At the third column down the nave, admire Raphael's blue-robed Isaiah, said to be inspired by Michelangelo's prophets on the Sistine ceiling
(Raphael, with the help of Bramante, had taken the odd peek at the master's original against strict orders of secrecy). Directly below is Sansovino's Leonardo-influenced sculpture, St. Anne and the Madonna with Child. As you leave, in a niche just inside the door, is the sculpted Madonna and Child, known to the Romans as the "Madonna del Parto" (of Childbirth) and piled high with ex-votos. The artist is Jacopo Tatti, also sometimes confusingly known as Sansovino after his master.
Piazza Sant'Agostino, Rome, 00186, Italy