Paphos The Great Mosque of Paphos: According to rural accounts, the original building was a church, which was converted to a mosque in 1570 by the Ottoman Governor Mehmet Bey Ebubekir and by the order of Selim Khan, (Selim II).
Pergamon There's now a mosque in one of the buildings of the Byzantine Red Basilica (wikitravel)
Thessalonika Galerius' Masoleum which was turned into a church (St Gregorios and not Demitrius) and then into a mosque.
Do you know of another WHS we could connect to Mosques converted from churches / cathedrals / synagogues?
Send it to me!