Seireitei

Seireitei (llit: Court of pure souls) is in the center of Soul Society, a circular shiro with four main entrances, each guarded by a Gate Guardian. The walls of Seireitei are made of stone called Sekkiseki (spirit reducing stone), a material known to negate all Reiryoku, similar to magnetic lodestones, preventing the ability to gather Reishi underneath your feet to walk in the air whist within Seireitei. The stone also forms a spherical barrier around the city. Stopping anything spiritual from breaching it.