More than a hundred years of research have revealed that the city was reconstructed at least nine times. The first settlement, referred to as Troy I, dates back to around 3000 B.C.; it lasted 5 centuries and was destroyed by fire. Schliemann's groundbreaking discovery of King Priam's treasure was found on Level II, but later research established that this civilization would have existed more than 1,000 years before the Troy of Homer. It is unclear what caused the destruction of the successive three civilizations, but findings from the site indicate that by Troy VI, a new culture had migrated, probably from Mycenae, expanding on the area of preceding settlements. The year 1184 B.C. is traditionally accepted as the year in which classic Troy fell, allowing archaeologists to establish that the Troy of Homer most likely took place during the existence of Troy VII-A, which was analogously destroyed by fire around 1200 B.C. Abandoned for more than 400 years, the site went through repeated cycles of invasion and reconstruction until the 1st century A.D, when the city was rebuilt, apparently under the orders of Julius Caesar, and given the name Ilium Novum (hence the Iliad in Homer's title). The prestige of the city during the Roman period is reflected in its illustrious guests: Augustus Caesar, Hadrian, Marcus Aurelius, and Caracalla all slept here.

Archaeologists estimate that Troy is actually 10 times larger than the roughly 165-sq.-m (1,776-sq.-ft.) mound of ruins. The more significant discoveries to date are the Troy VI fortification walls, a megaron (aristocratic dwelling), the Temple of Athena and sacrificial altar, the Schliemann Trench (where it all started), a Roman theater, and a bouleterion (senate building).