Ra'visthul

Dnd landscape artwork commission, here's the description from the client:
Ra'visthul
In the expanse of the gloomy and rocky terrain, the only light visible is the light you conjure or the glow of the occasional bioluminescent flora and insects native to this land. On the horizon, however, you see beacons of color: a large ravine with six glowing rivers - yellow, blue, violet, green, orange and red from left to right - stream out from what appears to be a city beyond the ravine in the distance. This is Ra'visthul, the arcane capitol of the Middledark.

A trade route leads straight to the city, and there is a large bridge up ahead that travelers use to enter through the giant city gates. The city itself is massive - larger than probably any you have ever seen. It towers above the ravine, and it seems to be comprised of hundreds of buildings stacked on top of each other, all in shades of grey or purple. In the middle of the skyline is a black, skinny tower with dark, grey-and-purple stained glass windows that rises 20 storeys above all the other buildings. Although the spire appears narrower than it should be and is imposing in its height, it is oddly beautiful and elegant in its design. This is the Kiln, the seat of government - and the city's jail. Yet it is only one of two daunting spires. If the Kiln is a giant, imposing tower in the center of the city, the Reliquary, the city's wizard school and museum of the arcane, is its softer, more beautiful sibling. The 13-floor spire is constructed of a beautiful, light grey marble and seems to gleam and glitter in the strange pale light that illuminates Ra'visthul. Curving archways give shelter to a pair of nightsilver doors that look strangely inviting in the fog that rises from the pollution of the rivers.