In Herodotus's Histories he says the son of Priam took Helen to Egypt and when they tried to tell the Greeks that Helen was not in the city they did not believe the Trojans. He learned this from the Egyptians and believed there was enough evidence to support it. This detail was omitted from Homer's Iliad. Do Historians know why? Are there any other sources regarding the Greek sack of Troy?
Well, there are remains of a city called Ilion and/or Troy in northwest Anatolia; however, that doesn't necessarily make that place "the" Troy of legend or the one in the Iliad. This older post goes into detail about it.