The Vale of the Spine is a towering ridge of mountains that starts near the plane of Baaror and creeps spireward almost to the River Ma'at. A smaller spur of the mountain range separates for a brief space into two parallel ridges, forming a tight valley between them. The narrow peaks of each ridge curve inward, looming over the valley like the ribs of some insanely-huge (and thankfully, dead) beast.
The town of Ribcage is tucked neatly into this space, filling it entirely. The natives have walled up the gaps between the mountains, so travellers on foot have to use the large iron gates at each end of the valley. Once inside, visitors'll find that the town's full of towers and private keeps. Most houses are build of shiny black or smooth gray stone, and high-ups with wealth and power show it off by covering their cases in ornate decorations. The brick roads of Ribcage are the color of fresh blood.
The most impressive place in the town is the Citadel, the home of Quentill Paracs, the Lord of Ribcage. It's a self-contained city within a city. The walls are carved from solid blocks of obsidian and ebony, and its steel portcullis is laced with strange and exotic items. Any berk who catches a gander at the Citadel knows who runs this burg.
Outside the Citadel, the city's been divided up among five competing families, each with its own support. The different domains aren't walled off, but each group has checkpoints and guards to keep tabs on the traffic.
The Gate to Baator is a separate complex somewhere within the Citadel, which means a cutter's got to march right past Paracs' nose to find it. The gate itself is a tall, spinning pillar of red light, filled with dancing motes of silver (said to be the disintegrated remains of berks who tried to cross the Lords of the pit). The Clueless should be aware that planars don't call this the cursed gate for nothing.
People here tend to be hard-working, suspicious, and grabby. Unlike their neighbors in Torch, they live for more than just coarse jink. In Ribcage, the goal is power in all its forms - monetary, military, and magical. Influence is the coin that pays the bills, and a basher with an edge over his fellows had better use it, or it'll be wretched away.
Most of the population is tiefling, with a strong dose of lower-planar blood coursing through their veins. There are also humans, evil humanoids, bariaur, githzerai, and a few other races present, but the tieflings have the edge, and having the edge is all that matters.
Most visitors are surprised to find few natives of Baator in Ribcage. Fact is, Lord Paracs and the senators have little love for the Lords of the Nine. They don't want to see their town get sucked into that infernal plane, and they do what they can to keep fiends out.