The al-Qarawiyyin Library
The oldest working library in the world, it was founded in 859 CE. The library was founded by Fatima Muhammad Al-Fihri Al-Quraysh, aka Fatima El-Fihriya, the daughter of a rich immigrant from al-Qayrawan (Tunisia today).
Well-educated and devout, she vowed to spend her entire inheritance on building a mosque and knowledge center for her community. According to UNESCO, the result is the oldest operational educational institution in the world.
The al-Qarawiyyin includes a mosque, library, and university.
Image taken from this tweet by Bayit Al Fann.