America's fascination with history

Most of said buildings were erected during periods when America was staunchly isolationist, which precludes any notion of being a glorious empire reminiscent of Rome or Greece. Heck, if you listen to the rhetoric against the war in Iraq today, you will notice almost all of it boils down to isolationism--this time from the Democrats (historically it was the Republicans (before Reagan) who were isolationist).

As for the battlefield re-enactments, I think that is partly also due to our lack of vicious losses to next door neighbors and a need for good relations with the neighbors. We can re-enact the Civil War all day long and the people who got whipped take pride in it. Imagine Germany holding a War of 1870 re-enactment, or worse, a WWII re-enactment of their invasion of France. That might hurt business over in France a tad. Notice we and the Canadians don't have any War of 1812 re-enactments (that I am aware of) or Revolutionary War re-enactments commemorating our invasion of Canada. And people call the war in Iraq a fiasco....

If I'm not terribly mistaken, the Brits have some events that come close to re-enactments for certain key naval engagements (like Trafalgar, or the one where they whipped the Spanish Armada), or air engagements (like the Battle of Britain).

Moving away from strictly talking about re-enactments and moving on to other martial displays, the US is hardly alone there. Russia's May Day parade showcased their military hardware to show their people just how badassed the Soviet Union was. The Paris Air Show (and Farnbourough and others) are really a demo for military aircraft sales (including to your own government and people--i.e. the Air Force showing Congress and/or the people who vote for Congressmen why we need new F-22s).

I think there's some merit to your argument about our relative youth and need to prove ourselves, however. I get the feeling that our politicians were always treated as some JV team second stringer by the big European powers until well into the Cold War--and even then. Just look at the way De Gaulle talks to his US counterpart around the time he booted NATO out of Paris. However, I don't think it's empire we seek, but more of Wilsonian idealism. One of the contributing authors to Makers of Modern Strategy: Machiavelli to the Nuclear Age suggests that while everyone else in WWII was struggling to survive and later to maintain their empires after the war, the US and the Soviet Union had an ideological struggle. I think the fondness for monarchy is romanticism, but what people really mean when they talk about American "imperialism" is our penchant for trying to make everyone else into Jeffersonian Democrats because we think they want to be free.