Bible question

Ok do Drudgereport.com has a report today about finding the well where Jesus put the mud on the blind guys’ eyes allowing him to see. This well has been lost for some time, in fact it's been lost long enough for someone else to claim they have that particular well. At any rate how does a city that's several thousand years old and with so much history continue to build on its self to the extent that they have covered over enough artifacts to where any place they dig they are going to find something else that's several thousand years old. I guess I don't understand how a city can continue to rebuild its self so many times that it is continuity coving over locations that are key to the propagation of its faith and that of Christ's time on Earth. Maybe it's a Judaic cover up to destroy all the places Jesus went and discredit that fact he was in that city, who knows. I understand that not everyone thinks Jesus was real and those who do haven’t always thought he’s worth the acclaim and of course the march of time and progress. Still it’s amazing that this city is literally built on top of the structures from centuries ago. San Francisco and parts of New York are built on a garbage heaps so maybe it shouldn’t surprise me that Jerusalem is too.