Originally built during the 4th century and rebuilt in the 12th century, this is one of Rome's oldest and grandest churches. It is also the earliest foundation of any Roman church to be dedicated to the Virgin Mary. With a nave framed by a processional of two rows of gigantic columns (22 in total) taken from the ancient Baths of Caracalla, and an apse studded with gilded mosaics, the interior conjures the splendor of ancient Rome better than any other in the city. Overhead is Domenichino's gilded ceiling (1617). The 18th-century portico draws attention to the facade's 800-year-old mosaics, which represent the parable of the Wise and Foolish Virgins. They enhance the whole piazza, especially at night, when the church front and bell tower are illuminated. The church's most important mosaics, Pietro Cavallini's six panels of the Life of the Virgin, cover the semicircular apse. Their sense of realism is said to have inspired the great Giotto. Note the building labeled "Taberna Meritoria" just under the figure of the Virgin in the Nativity scene, with a stream of oil flowing from it. It recalls the legend that a fountain of oil appeared on this spot, prophesying the birth of Christ. Off the piazza's northern side is a street called Via delle Fonte dell'Olio in honor of this miracle.