What is the difference between classical and modern archeology?
Contrast this
http://en.wikipedia.org/wiki/Troy
with this
http://en.wikipedia.org/wiki/Archaeology
Schliemann didn't intend to be destructive, but he was. Modern methods are far more careful so that artifacts are not lost to people who dig deep trenches!
This is interesting, too.
http://www.angelfire.com/hi5/interactive_learning/Archaeology/modern_archaeological_field_meth.htm