The prison was in the Central Endowments Library (maktabat al-awqaf al-markaziyya) in the Nabi Shith area in Mosul. The library, which was built in 1972, included rare books and manuscripts. After its capture of Mosul in 2014, ISIS seized the library, confiscated its books, then converted it into a security prison to hold members of the Iraqi army and Peshmerga. According to former detainees interviewed by the IPM, this prison was highly secret and heavily fortified. Iron doors were used instead of wooden doors, and windows were painted black to block detainees from seeing through them. Witnesses talk about ISIS beheading Peshmerga fighters on Mosul’s bridges before withdrawing from the city in 2017. They add that those fighters had been detained in the Central Endowments Library Prison after being captured in the Talkif battle. After the expulsion of ISIS from Mosul in 2017, the library was restored, but without its most important books. It now contains books donated by civil society organizations and individuals.