A claim from several articles (e.g.) about a major find in India runs thusly:

"It's a huge city that existed about 2,500 years ago. The city had four gateways and could have housed up to 25,000 people. Even classical Athens had only 10,000 people," another archaeologist, RK Mohanty, was quoted by the newspaper as saying.

I'm not sure where this "10,000" people claim comes from. Just from memory, the figure I remember from various claims is that Athens+Attica was roughly 250,000 to 300,000; male citizens were roughly ten percent of that. Even estimating conservatively, I think that puts a lot more than 10,000 in the city, no?