In the year 1400, in the city of Rome, people would wander around looking up at the ruins of a city that had once been great. Inside the broken walls that had been smashed in 410 AD were the remains of huge temples, sports arenas, public baths, apartment blocks and palaces. Nearly all of them were ruined and could not be used. Nearly all of them were half-buried in the dirt. A lot of them were pulled down to use as building stone. But they showed people what great things could be done. Among the ruins of this once-great city, the people of Rome lived in cottages. They still went to church in the huge churches (basilicas) built by the first Christian Emperor, Constantine the Great, in the 4th century. They still held a market day in the Ancient Roman market place of "Campo Dei Fiori" ("Field of Flowers").