12. This mosque is supposed to be the place where Ali, the fourth caliph, was assasssinated.
From Quiz Famous Mosques
Answer: Mosque of Kufa
Ali was Mohammed's (P.B.U.H.) first cousin and son-in-low, and became the fourth caliph in 556 AD. During his short reign, he faced many challenges and opposers. Aisha, the Prophet's wife, declared war on Ali, but her army was defeated outside Kufa, Ali's capital. Mauwiyah, the governor of Syria, rebelled. Ali led armies into a year-long battle against Mauwiyah at Siffin. Later, a truce was signed. The Kharjites, a group of people that had supported Ali at Siffin, revolted, and Ali sent armies to subdue them. In 561, a Kharjite, Abdul Rahman bin Muljim, stabbed Ali on the head while the latter was leading the morning prayers. Ali passed away two days later. The mosque is located in Kufa, and is an important pilgrimage site for Shia Muslims.