Al-Khamis Mosque in Bahrain, one of the oldest Islamic buildings in the Gulf, is believed to have been built by the Umayyad Caliph Umar bin Abd al-Aziz in 692 A.D. A UNESCO report noted that the corners of the surrounding wall had imitation circular bastions of a type known only from very early mosques of the 7th to 9th centuries. However, an inscription found on the site and subsequently built into the doorway of the western minaret, suggests a foundation date during the second half of the 11th century.

The mosque was rebuilt twice, initially in about 1340 A.D., and again in the 15th century. The twin minarets were constructed during the latter phase. Three of the mosque's original carved timber beams are displayed in the National Museum.

Bahrain's medieval old city was situated just south-east of the al-Khamis Mosque on what was then coast.