Italian archaeologist, topographer, and authority on ancient Rome who discovered many antiquities at Rome, Tivoli, and Ostia. He published a 1:1,000-scale map of classical, medieval, and modern Rome in Forma Urbis Romae (1893–1901).

At 20 Lanciani assisted in the excavation of Emperor Trajan's harbour at Porto, and his description (1868) of that site remains authoritative. He was appointed director of excavations and professor of ancient topography at the University of Rome in 1878, and he also lectured in the United States and England (1886–87). His major works include Ancient Rome in the Light of Modern Discoveries (1888) and Storia degli scavi di Roma, 4 vol. (1902–12; “History of the Excavation of Rome”).