Positioned just below the Renaissance basilica and above Constantine’s 4th century basilica, the grottos contain chapels dedicated to various saints and tombs of kings, queens and popes, dating from the 10th century. The holiest place is Peter’s tomb, containing the "memory", built in the 4th century by the Emperor Constantine, on the spot were the Apostle’s tomb was venerated. In one of the chapels around the apse is a fresco by the 14th century Roman painter Pietro Cavallini. It is called the “Madonna della Bocciata”, because of Mary’s swollen face. According to an old legend, her face bled because a drunken soldier had thrown a bowl into the holy image after he lost a game of bowls. The monuments to Paul VI (1978) and Pope John Paul II (2005) are also in the grottos.