The Gray Cliffs

The limestone cliffs near Graycliff are what earned the city its moniker. Over 140 paces high at their tallest point, the cliffside is considered a safety hazard due to unstability. As such, on the surface fences have been placed to prevent anyone from approaching the edge. Watchtowers are in place to oversee that nobody approaches the cliffs, to make sure no child falls to their death.
The cliffs are gray due to the Graycliff Floating Harbour. Because of the rough terrain, ships cannot land within a hundred miles from the city. As such, a floating set of docks was constructed, tethered to the cliffside with large chains. Cargo is transported to and from tunnels in the cliffside with steampowered cable cars. The resulting smoke has turned the cliffs gray over time.
The reason tunnels are used, is because the surface area of the cliff is not trusted. As such, no construction is done anywhere near the cliffside. The tunnels stretch for over a mile towards Graycliff. The city underground has several public entrances, and also doorways leading to many companies their basements. It is estimated that about a sixth of the city's indoor surface is underground.