Synagogue

Parthenon was used as a Christian church from the 6th century, and turned into a mosque between 1456 and 1687.
See en.wikipedia.org

Our Lady of Ljeviš was converted to a mosque during the Ottoman Empire and then back into an Orthodox Church in the early 20th century.

"There is also a possibility that at least one of the churches was converted into a mosque after the Islamic conquest." (AB Ev)

Tomb of the Patriarchs

Was a Visigoth church before being converted to a mosque in 784. Became a Church again in 1236.

There is a Crusader church in Bet Guvrin used by the Knights Hospitalers. It was later converted into a mosque

Galerius' Masoleum which was turned into a church (St Gregorios and not Demitrius) and then into a mosque.

The Cathedral of Syracuse "was converted into a mosque in 878, then converted back when Norman Roger I of Sicily retook the city in 1085." (wiki)
See en.wikipedia.org

There's now a mosque in one of the buildings of the Byzantine Red Basilica (wikitravel)

"Ketchaoua Mosque" was re-created in 1962 from "Cathedral of St Philippe" which itself had been created from the Ketchaoua mosque in 1845.

"Hagia Sophia" became "Ayasofya Mosque" from 1453 -1935 (Now a museum); "Saint John the Forerunner by-the-Dome" (12th C) became the "Hirami Ahmet Pasha Mosque" in late 16th century

In 705 the "Church of St John" was rebuilt as a mosque (immediately after the Muslim conquest in 636 it was shared between Christians and Muslims). Now known as "Umayyad Mosque".

During the time of Ottoman rule St. Clement's Monastery church at Plaosnik was transformed into the Imater Mosque. The mosque did not survive the end of the Ottoman Empire.