/ Shanghai is the world's largest city, with 18 million people living within the city limits, so it is filled with action and ideal people-watching conditions, with this densely-packed population. Shanghai is also one of the world's most modern cities, which might surprise those who think that China is not yet a developed nation. Glistening new skyscrapers make this the largest collection of tall buildings on Earth. Despite this gigantic scale, it is a great place to discover on foot.