Name the city that is at the exact center of each circle you see on the map!
If you want to know how they were chosen: put a circle of radius 15 at the location of the world's largest city. Now put one for the next largest city that doesn't touch the circle you already placed. Keep going, making sure no previously placed circle is touched!
Data for 1M cities from citypopulation.de, data for smaller cities from geonames.org
Answers are sorted alphabetically
Cities with no more than 10,000 inhabitants are only considered if they have no larger city within 100 km
I also found the instructions confusing. You make it sound like the quiz has to be completed in a specific order, from the largest city on the map all the way down to the smallest. Wouldn't it be simpler to just say "Name the largest city within each circle shown on the map"? Or am I not understanding something? Sorry to sound so critical - this is an amazing concept!
I'll try explaining in a different way: the circles were added in a specific order: circle around Guangzhou as it's the biggest city, then 2nd biggest etc as long as the circle you add doesn't overlap any circle that's been added already. So you are not looking for the largest city inside a circle but for the one that is at the very center of the circle. This can lead to odd situations like the ones Jerry pointed out: Darwin can't be added because it would touch a circle but Palmerston, only a few km away, can! I could have made the circle with twice the radius as that would highlight the area where you can't have new cities, but then there would have been lots of overlapping. I thought that leaving the circle as 'zoomable' would be helpful in pinpointing where the city you are looking for is. Anyway, after reading Jerry's comments I prepared a quiz where you guess largest cities in circle!