Trescanta is a gothic/victorian city in many ways.
It is an old city, during an apocalyptic event it was a place of shelter, but towards the end, it was struck by a meteor that caused a seismic event that split the city into three distinct tiers.
For a time the city was infested with monsters due to the nature of the meteor, but some parts have been reclaimed.
Before the catastrophe, the city must have been a place of wonder, as there are some distinct wonders that remain.
The slums are set in the old city, though they are now clogged with refuse and in disrepair, there are signs that they were beautiful neighbourhoods separated by well-kept streets and canals.
The three tiers of the city are quite neatly used to separate the city's socio-economic tiers. Basically the higher you go the better the neighbourhoods. You have Hightown, Midtown and Lowtown as the three colloquial tiers.