At the museum in Olympia, you can see a Persian helmet sent to the sanctuary by the Athenians from Marathon.
It's amazing.
Somewhere one of the shields taken by the Athenians from a Spartan on the isle of Sphacteria, and so engraved. Had Athens been a multicameral democracy, instead of the mob-ocracy that it was, that battle might have ended the Peloponnesian War, and in any case, there wouldn't have been the expedition to Syracuse. Ah well, it worked out anyway, as Thebes destroyed what was left of the Spartan army at Leuctra. That monument remains (much reduced by earthquake and scavenging for building stone). Oh wait, it's a restoration. Still, some of it was still in situ. As you said, amazing.
http://www.sikyon.com/Thebes/leuctra_eg.html