Largest City in the World

Recently, Mumbai (Bombay) became the Largest City in the World

Interesting conversation:

Me: Bombay is the largest city in the world
Not me: (Look of surprise followed by) Oh, you mean by population

I bet that explanation was not necessary all these years while it was some Western city at the top.

As an aside, the largest urban conglomerates (as opposed to within the city limits) are Tokyo, NYC, Mexico City, followed by Mumbai and Sao Paulo.