Harrapa

The great spiral walls of Harrapa are famous the world over, though perhaps not as famous as the city's unique spider silk. Located in the southern central portion of the Great Continent, Harrapa and its neighbors enjoy good relations among each other, but their flat arable land makes a tempting target for the horse nomads and various empires who would conquer their land to serve as a breadbasket. Though the Emperor of Balleron has yet to turn his sights so far from his current holdings, most Harrapani believe it to be a matter of time. 
The city's spiral walls are unique in the world, and maintain a spiritual as well as practical significance. From the south side of the main gate (the outermost point) there are seven walls, with the spiral ending in the magnificent keep where the government is seated. A raised highway runs right up the wall itself with the gate required a turn to the east, to better deter siege equipment. The genius of the walls is that they offer invaders a path of least resistance, though running around the spiral leaves any invading army exposing to constant reprisal from atop the walls. No invading army in Harrapa's three thousand year history has ever made it to the center, with the furthest finally stopped at the third wall.
The seven layers of the spiral also represent chakra, with each color housing businesses and buildings appropriate to that chakra (in theory).

Assets

The rare cocoon-spider lives only in this region, and Harrapa has capitalized on the curious arthropod to fashion the strongest silk weave in the world. The cocoon-spider requires human intervention, and was a gift from the gods themselves; their cocoons are too strong for them to break free on their own and require careful tending. The Spider Keepers are the most powerful guild in the city, and their spidersilk garments are highly valued even by the elves for their ability to stop injuries and bullets. Requiring a less specific weave than standard silk for its bulletproof properties means that spidersilk can also be fashioned into rather ordinary looking clothes that retain its incredible strength, though the material has difficulty accepting certain dyes.