The largest one by the "city proper" definition, is Shanghai with a population of 24 million! Earlier this week I spend three days in this East-Chinese mega-city which has changed unbelievable over the last few years.
The image above was made from one of the most famous viewpoints in Shanghai, "The Bund". Carrying my sturdy Gitzo tripod on the trip proved worthwhile! Even though a bit more clouds would have made it even more worthwhile...
It was unfortunate that the Oriental Pearl tower (highest on the left) for some strange reason was not lit while I was there... Another reason to go back, I guess.
Nikon D800 with the 14-24 2.8 Nikkor lens
ISO 100, f4.5, 20mm, 4s
RAW development in Lightroom 4.3 (RC)
Nik ColorEfex Pro for contrast and sharpeness