Seireitei

is in the center of Soul Society.

Overview
Seireitei is a circular shiro with four main entrances, ten days walk apart,, each guarded by a Gate Guardian. These gates are called the (in the North), the  (in the East), the  (in the South) and the  (in the West). The gates are so heavy that it takes the full might of Jidanbō Ikkanzaka to lift one, while during the Bount-led attack on Seireitei, siege machines were needed to open the gates. There are, however, doors within the gates, as seen when Momo Hinamori first entered the Shinō Academy.

The walls of Seireitei are made of, a rare type of stone known to negate all Reiryoku, similar to magnetic lodestones, which prevents 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, extending above and below, stopping anything spiritual from breaching it from ground level, from the sky or from underground.

The majority of the residents of Seireitei, nobility and Shinigami alike, do not interact with the citizens of Rukongai. However, residents of Rukongai, like Renji and Rukia, are allowed to apply for the Shinō Academy, which is often the only escape from the poorest conditions of Rukongai.

Gate Guardians
The Gate Guardians are the guardians of the four gates of Seireitei. They are all giants who have the strength to lift the gates made of Sekkiseki.