Elderly Romans still like to talk about their first vivid glimpses of the G.I.s on that day, sixty years ago. When the advance units of General Mark Clark’s Fifth Army appeared in the city, the Romans weren’t sure if they were Allies or Germans; their clothes and vehicles were so dusty that the insignia were obscured. But when the soldiers took out their cigarettes, and the people saw that they were smoking Camels, they knew the Americans had arrived. Italian women climbed up on tanks to kiss the grimy faces of the G.I.s. As the historian Robert Katz recounted in his book “The Battle for Rome,” an American soldier named Thomas Garcia, on seeing the Colosseum for the first time, uttered the immortal words “My God, they bombed that, too!”