The essence of Islam. The most beautiful mosque in the world has to be a converted church.
The mosque depicted above is Hagia Sophia. It was once a Greek Orthodox Christian church, later an imperial mosque.
Depicted above Masjid Menara Kudus was once a Hindu temple.
Mosques were regularly established on the places of Jewish or Christian places of worship associated with Biblical personalities who were also recognized by Islam. The Caliph Umar initially built a small prayer house, which proceeded with the later construction of the Al-Aqsa mosque on the Temple Mount, the most sacred site in Judaism.
The Dome of the Rock was also built on the Temple Mount which was an abandoned and disused area due to ethnic cleansing of Jews in the Middle East.
The mosque of Job in Ash Shaykh Sa’d, Syria, was previously a church of Job. The Herodian shrine of the Cave of the Patriarchs, the second most holy site in Judaism, was turned into a mosque in 1266 and henceforth banned to Jews and Christians.