I'm not sure in the end that people get the best of the Americas or of Africa by visiting any city, no matter how great. If one had limited time to visit those continents, surely it's all about the great outdoors. Europe to me is the continent of the great old cities, and I'm sure we can at least all agree on Paris. It would be hard to just pick three top European cities though. Kyoto for Asia but I haven't visited any others yet. It would be difficult to believe that many can hold to this standard of beauty, though.

In Africa the only city I visited was Nairobi, which I believe they told us had only 300 people in 1903 and in 2004 had 5 million! It is too young to be historical, but I did like the way you could capture photos of wildlife in Nairobi National Park with the skyline in the background. I have a nice one I'm rather proud of with a giraffe.

Perhaps the person who suggested Panama City, Panama for North America had a similar experience with the beauty of the rain forest park right in the capital city like that. Get your toucans and Black-Hawks right in town!