Magdoral

The underground city of Magdoral is effectively built in an absolutely ginormous cave, around the main spring of the river Bellrath.

The city is built in layers, as it's been built over hundreds of years by quarrying out under the mountain. the upper layers with the bellrath spring are the "nice" layers, where mostly the rich merchants, nobility and high-ranking dwarves from corporations have their homes or offices.

the further down you go, layer by layer, the city turns more towards a working class area. going from nobility down to working class is as follows: The lower levels are actually only used for mining, tunnels going everywhere and the main plaza being full of cranes, minecarts, materials for rails and such. Down the side of one of the walls, all the way to the top there is a small waterfall coming from the lake that powers water wheels, which in turn power the pulleys and cables that take the ores to the surface.
 * noble layer, only the richest dwarves with the most priveleges, these buildings are often ornately decorated with masonry.
 * merchant layers, where most of the shops are and some offices for the smaller corporations to buy ores and such.
 * guild layers, where the smiths, smelters, craftsdwarves and occasional military personnel hangs out
 * miner layers, where the mines start. the upper few miner layers are just quickly put together holes in the walls of the quarry where beds are put so the miners can sleep somewhere.

the entire city is lit in dim blue-green light, there are rocks in the walls, floors and lanterns on the sides of buildings. all the way at the top of the city there is a small skylight through which you can see a small beam of sunlight which at midday shines exactly at the top of the waterfall during summers, and exactly at the middle of the lake during winter. (so lake is north in the city, waterfall leads south, river leads east and )