The Forum, once marshland prone to flooding and eschewed by Rome's Iron Age (1000-900 BC) inhabitants, spreads from the Colosseum west toward the Capitoline Hill. Today, many of the Forum's structures are reduced to piles of jagged rocks, and the locations of many sites are just hypotheses.

In the 7th and 8th centuries BC, Etruscans and Greeks used the Tiber Island as a crossing point for trade and the Forum as a market. Rome was founded as a market town for sober farmers who came to trade and perform religious rites; the Romans were peacefully dominated by the more advanced Etruscans until 510 BC, when the Republic was established. The Curia, the meeting place of the Senate; the Comitium Well, or assembly place; the three sacred trees of Rome; and the Rostra, the speaker's platform, were built here to serve the young government. The earliest temples (to Saturn and to Castor and Pollux) were dedicated in honor of the revolution. The Via Sacra, Rome's oldest street, became the main thoroughfare of the young city. The conquest of Greece in the 2nd century BC brought new architectural forms to the city, including the lofty Basilica Aemilia, used as a center for business and judicial work before Christians transformed many of the existing structures in the Forum into churches. The Forum was never reserved for a single activity. Senators debated the fates of far-flung nations over the din of haggling traders. The Vestal Virgins kept the city's eternal flame burning in their house on a street full of prostitutes (who kept flames of a different sort burning). Elsewhere, priests offered sacrifices in the temples, generals led triumphal processions up to the Capitoline, and pickpockets relieved tourists of their possessions. Some things never change.