Eberron - Return of the Lich Queen
Sharn is the most populous city in all of Khorvaire, and arguably all of Eberron. The city literally towers atop a cliff above the mouth of the Dagger River in southern Breland.
Sharn is known as The City of Towers, but has also been called many other names, including The City of Knives, The City of Lost Souls, The City of a Thousand Eyes, the Gateway to Xen’drik, and The Gateway to Perdition
Sharn is a vertical city. It is divided up into five distinct plateaus, as well as a district built into the sides of the cliff near the Dagger River. The five plateaus are known as Central Plateau, Menthis Plateau, Northedge, Dura, and Tavick’s Landing. And, Cliffside is a neighborhood perched on the side of the cliff. While each plateau divides the city into districts, the city is also stratified vertically and divided into several sections. The lowest wards of the city are called The Cogs, and if you were to walk to the heights of Sharn you would pass through The Depths, the Lower City, Middle City, Upper City, and then finally you would need to find some method of travel to the highest section of Sharn, which is Skyway. Generally, the higher you are in Sharn, the wealthier the citizens are.
For more info: Eberron Wiki