Does anyone know of a site showing the classic photos of the 20th century?

I’m looking for things like the man facing down a tank in Tiananmen Square, and Krushchev beating on a desk with his shoe in the UN. If anyone could find a link for me, I’d appreciate it.

I like this one. It has a special section for new photos.
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Here’s Tiananmen - Many photos

Krushchev was more trouble, but here he is at the Empire State Building

Obviously American-centered, but the Library of Congress has some great photo stuff available here:
Choose photo collections and then follow the search protocols.

Don’t know if it’ll have what you’re looking for, but it’s a neat site.