To be fair, not everybody knows all 7 wonders of the world. I know the Pyramids at Giza, the Hanging Gardens of Babylon, the Colossus of Rhodes and the Library of Alexandria.
7 Ancient Wonders: Great Pyramid, Hanging Gardens, Mausoleum, Statue of Zeus, Temple of Artemis, Colossus of Rhodes, Pharos Lighthouse. 7 other wonders (forgot the name): Taj Mahal, Petra, Colosseum, Statue of Christ, Great Wall, Chichen Itza, Machu Picchu.
Have only heard of mesas in Finnish and German (pöytävuori and Tafelberg), didn't know the English name. (Should have gotten it through Latin.) So it can be a problem for those who speak germanic or slavic etc. languages.
I got most right apart from the U city in Netherlands, and mesa. I have to admit, I don't think I have ever heard of mesa! Maybe it is more well-known in American English?
I recall something about the circumference of the Earth being largest several degrees lower than the equator, not actually at the equator. I understand the intent of the question but maybe something liked "assumed to be the largest circumference of the Earth"
"Large Southern African semi-desert" made me think there was a general term starting with K that described that type of biome and I just couldn't figure it out.
"Large semi-desert in Southern Africa" probably wouldn't have a similar effect on my brain, which is interesting.
Some other good obscure answers in here though....nice work :)
"Large semi-desert in Southern Africa" probably wouldn't have a similar effect on my brain, which is interesting.