What is "shabestan"

A shabestan or shabistan is an underground space that can be usually found in traditional architecture of mosques, houses, and schools in ancient Iran.

These spaces were usually used during summers and could be ventilated by windcatchers and qanats.

During the Sasanian Empire and the subsequent Islamic periods, "shabestan" also referred to inner sanctums of the shahs where their concubines resided. Later these structures came to be called zanāneh (feminine residence), andarouni (inner private zone) and haram (from Arabic harem).