Built in what was once a marshy valley between the Capitoline and Palatine hills, the Forum was the civic heart of Republican Rome, the austere enclave that preceded the hedonistic society that grew up under the emperors in the 1st to 4th century AD. The area was once filled with stately and magnificent buildings -- temples, palaces, shops -- and crowded with people from all corners of the world. Today this series of ruins and marble fragments interspersed with crumbling columns is impressive, but it's not easy to envision the grandeur that once was. It may help to bear in mind that what you see today are the ruins not of one period but of almost 900 years, from about 500 BC to AD 400.

Rome's timeless landscape is suggestive enough that you will probably be content to wander, letting your imagination dwell on Cicero (106 BC-43 BC), Julius Caesar (100 BC-44 BC), and Mark Antony (circa 81 BC-30 BC), who delivered the funeral address in Caesar's honor from the rostrum just left of the Arco di Settimio Severo. This arch, one of the grandest of all antiquity, was built in AD 203 to celebrate the victory of the emperor Severus (AD 146-211) over the Parthians, and was topped by a bronze equestrian statuary group with six horses. Most visitors also explore the reconstruction of the large brick senate hall, the Curia; the three Corinthian columns (a favorite of 19th-century poets), all that remains of the Tempio di Vespasiano (Temple of Vespasian); the circular Tempio di Vesta, where the highly privileged vestal virgins kept the sacred flame alive; and the Arco di Tito, which stands in a slightly elevated position on a spur of the Palatine Hill. The view of the Colosseum from the arch is superb, and reminds us that it was the Emperor Titus (AD 39-81) who helped finish the vast amphitheater begun by his father, Vespasian. Now cleaned and restored, the arch was erected in AD 81 to celebrate the sack of Jerusalem 10 years earlier, after the great Jewish revolt. A famous relief shows the captured contents of Herod's Temple -- including its huge seven-branched menorah -- being carried in triumph down Rome's Via Sacra. Audio guides are available at the bookshop-ticket office at the Via dei Fori Imperiali entrance. COST: Free, guided tour EUR3.50, audio guide EUR4.