Check out the central square in Warsaw's old town. Looks like a nice little square from a few hundred years ago, doesn't it?
Well, it's not. Warsaw got destroyed during the second world war, the old town included. After the war, the government used photographs and detailed plans of the old town to reconstruct it; everything looks old, even from up close, but it dates from the 40s to the 60s. On the one hand, this means the old town is a big old fake - but it's also kind of cool that they put that much effort into reconstructing their history.
I was in Warsaw for less than 24 hours. The coolest sight, which for some reason I took no pictures of, was the museum of the Warsaw Uprising (for reasons that are unclear, they call it the Warsaw Rising Museum). It's a huge new museum with great exhibits, lots of photos and documents and videos and whatnot.
The Warsaw Uprising, not to be confused with the earlier Warsaw Ghetto Uprising, was toward the end of the war. The Nazis were about to leave and the Red Army was coming from the other direction. So Poland was like, ok, if we don't establish our own government right this second, we're going to be overrun by the Soviets. (It didn't work out.)
(The Ghetto Uprising didn't succeed, either. Read about the Warsaw ghetto here and the uprising here.)