Qiblah

In Islam qiblah refers to the direction in which the performer of ritual prayer faces. In fiqh, facing the qiblah becomes a necessary condition for the performance of a number of religious rites as well as non-ritual actions, such as slaughtering an animal. Apart from its applications in fiqh and from the standpoint of Islamic culture, the qiblah implies a spiritual pole for all Muslims, who consider turning toward that direction as a means of drawing nearer to God. In the first few years after the advent of Islam Biyt al-Muqaddas (Jerusalem) was the qiblah of Muslims, but as result of a divine command the Ka`bah became the new qiblah (Baqarah 2: 144, 149 – 150). Therefore, in Islamic culture Biyt al-Muqaddas is referred to as the old (`atiq) and the first qiblah. 

According to fiqhi rules regarding the need for facing the qiblah during the ritual prayer, those within Masjid al-Haram must face the Ka`bah, those within the Haram (sanctuary, i.e. Mecca) must face Masjid al-Haram, and those outside of the sanctuary must face Mecca. However, the requirement to face qiblah is lifted in cases of imminent danger, such as during a military engagement.

* source: Gorji , Abolghasem "Islam Entry" The Great Islamic Encyclopedia. Ed. Kazem Musavi Bojnourdi.Tehran: The Center of Great Islamic Encyclopaedia , 1989-, V.8 ,pp.409