Dunmore was, until very recently, the largest city in the world. Unlike the current contender, Bala, it is entirely above ground, and sprawls over several miles. The buildings are a combination of brick and metal, with ceramic rooves. Along the cobblestone streets are gas lamps, and the occasional public drinking fountain. Public carriages follow set paths ever thirty minutes, and are also provided for free.
The most amazing features of Dunmore are under the surface, literally. Every house and building has three "utilities" run to it. First, there is the gas line, where natural gas is run to various lamps and heaters in the building. The second is a water pipe; every building has indoor plumbing. Water pressure is provided by water towers across the city, each of with are maintained at an acceptible level by workers who refill the towers ever few days.
The third pipe, however, is one of the most impressive. A pneumatic system runs the entirety of the city, and allows for the sending of letters, small packages, and, if properly packaged, food. The pneumatic system is the work of Gerel's current ruler, King Throop.
I've modeled this city off a slightly more steam-punk London, circa 1790ish.