The story so far:
Historians tentatively agreed that the city of Troy should be sought at the south end of the Trojan Plain.
Schliemann, a wealthy businessman and Homer enthusiast, in collaboration with Frank Calvert, another enthusiast, began digging at Hisarlik, convinced that some of the lines in The Iliad pointed to that location. He was able to unearth something.
This something was subsequently ridiculed, labeled fake, etc., by historians, because nobody likes a smart ass. Schliemann's methods and believes have been repeatedly vilified by academia. Today, folks seem to agree that what Schliemann discovered was not Troy, but its predecessor; and that his methods were so crude that the actual city of Troy, sitting higher than Schliemann thought, was destroyed during the excavation. However, there seems to be an agreement that Schliemann's choice of location was actually accurate.
(A side note: I've read The Iliad too, but in all honesty I wouldn't know where to start digging. Why Hisarlik, especially? Why not a hundred miles south of it?)
It is said that the reason for the siege, apart from the kidnapping and adultery, was that Troy served as some sort of a customs checkpoint, a coastal toll booth that charged Greek merchants an exorbitant fee for passing through. I have no idea whether this story has any scientific basis. I've looked; I haven't been able to find anything to support it.
My question is: what did Schliemann discover? Is it really Troy? And if so, how do we know this?