Join an expert guide to explore the Catacombs of San Sebastiano, originally a pozzolana quarry used for Christian burials in the 2nd-3rd centuries AD. See the Mausoleums of the Innocentiores and the Axe with elegant stucco decorations, and rooms housing martyrs' tombs that attracted medieval pilgrims. Tours daily 10am-4:20pm, lasting 30 minutes, in Italian or English. Wear appropriate shoes and clothing for uneven floors and cool temperatures. Photos/videos not allowed.