A Colder War
Sharn is the most populous city in all of Khorvaire, and arguably all of Eberron. The city stabs skyward from a cliffside overlooking where the Dagger River meets the Thunder Sea. 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, and The Gateway to Perdition.
Sharn looms atop the cliffs overlooking the Hilt, a bay at the mouth of the Dagger River in southern Breland. The city sits upon the foundation of an ancient hobgoblin city. Below that, a rumored lake of molten lava rests; its presence can be felt only in the lowest parts of Sharn, the Cogs.
The inhospitable outcropping that Sharn sits on allows the city to grow only in vertical height. This might have been a problem for other cities, but Sharn happens to be located within a manifest zone linked to the plane of Syrania, the Azure Sky. The manifest zone enhances magic that creates flight and levitation. This allows Sharn to have towers that rise nearly a mile in height, transportational flight, and even a section of the city that floats above the highest towers.