Player's City Guide

From the introduction:

Waterdeep is the largest and most powerful city in the north Sword Coast. The population of Waterdeep itself is around 200,000, while hundreds of thousands more live in the surrounding areas under the protection of Waterdeep. The last century hasn’t been kind to the City of Splendors, but it is quickly regaining its former glory. Eminently defensible, Waterdeep is built on a raised plateau, protected from the elements by Mount Waterdeep, and secured by stout walls and steep cliffs overlooking the valley below. Waterdeep is named for the excellent deep water port on the southern end of the city.