http://www.sacredsites.com/middle_east/lebanon/baalbek.htm
In the year 634, Muslim armies entered Syria and besieged Baalbek. A mosque was built within the walls of the temple compound, which was itself converted into a citadel. Over the next several centuries, the city and region of Baalbek were controlled by various Islamic dynasties including the Umayyads, Abbasids and Fatamids as well as the Seljuk and Ottoman Turks. During these years, Baalbek was ravaged by the Tartars in 1260, Tamerlane in 1401 and was also shaken by numerous powerful earthquakes.
Look at some pictures of Baalbek and Bekaa valley, there are many archealogical treasures there.