The bulk of Geb’s undead legions, mostly zombies and skeletons, are stationed in the city of Yled, near the border with the Mana Wastes. The Bonewall, a vast barrier of bleached bones, encircles the city, and can be animated by the Blood Lords to defend the city in case of siege. Yled is Geb’s largest city, and home to a variety of necromantic colleges and research laboratories. The most famous of these is the Mortuarium, a twisted tower that sticks up above the city’s skyline like a withered, clawed arm.
Sources: Pathfinder Chronicles Campaign Setting