Princes' Heights were the oldest parts of Chammur, where the living quarters were cut directly into the stones. By 1039 KF those parts of the city were inhabited by the poorest residents of the city, who couldn't affort any better place, like Evumeimei Dingzai and her cats. Evvy also lived there because of her stone magic, which made her like the stones and the stones provided protection to her, for one making her den invisible to anyone else. The Heights were dark, smelly and narrow.
Because of their old age and the various magical influences over the centuries the stone has become weak, making the Heights prone to cave-ins.