ORIENTATION, a term expressing the angular 'elation of any object to the points of the compass; in architecture, used to express the relation of the main dimensions of a building, with reference to the points of the compass, and especially with ref erence to the east. In Mesopotamia and Egypt, as well as in primitive Central America, orientation of buildings was common from an early date, with important features, entrances, passages and the like designed to point in the direction of the rising sun. In north Europe the same custom evidently prevailed, as Stone henge, near Salisbury, England, is carefully orientated. Many Greek temples were also designed to face the rising sun.
In the earliest Christian basilicas at Rome, the apse was placed at the west end, so that the priest who served the altar from behind, facing the congregation, himself faced the east and the rising sun. This orientation has sometimes been traced to the influence of the churches of the Holy Sepulchre at Jeru salem and of the Nativity at Bethlehem. It is more probable, however, that this orientation was due to an underlying tradition whose roots go far back beyond the origin of Christianity.
In St. Sophia, Constantinople, and all the Byzantine churches, the apse was placed at the east end, and the same custom obtains in the early churches in Syria and the Coptic churches in Egypt.
During the 6th and 7th centuries this orientation gradually came into use in Italy and the west generally. Orientation of this type, with the apse or altar toward the east, is gen erally carefully observed in Spain, Germany and England, and less carefully in France and Italy. It is so common, however, that in an architectural or ecclesiastical description of a church building, the "east end" is always the end with the apse or altar. In Mohammedan mosques the mihrab or prayer niche is so placed that the worshipper looks towards Mecca.
Orientation is an important consideration in the placing of any building, as exposure to the sun, or lack of it, prevailing winds and similar facts in climate must be considered in designing a building for any purpose. Thus in the northern temperate zone, living rooms are usually arranged to get large amounts of south light ; studios are arranged with north light, and, in general, build ings like schools, with rooms on both sides of a corridor, are placed, if possible, with the corridor running north and south, so that the rooms on both sides may receive the sun.