Hmm - The pyramids of Giza seem to stand out - one or two other architectural type things like the first skyscraper or something? And maybe something to do with the discovery of germs/viruses/bacteria (I'm sure this has a proper name, but I don't know what it is)/epidemiology? Something of that sort of medical ilk, anyway.

Oh, and flight - If they're not too close together, lighter than air/heavier than air (although that is debatable within a few years and several continents, last I paid any attention - my info could be old, though) and outside atmosphere or something?