The practise of turning toward the east in prayer, a pagan custom adopted by the early Christians who attached to it a new significance, for the East was man's original home, in the East Christ lived on earth, and from the East He will come to judge mankind.
Accordingly, they built their churches in "high and open places, facing the light," and buried their dead with feet toward the East.
The Apostolic Constitutions directed that churches be erected with the head or apse towards the East, and the custom was universally observed from the 8th century onward, though under Constantine the opposite system was temporarily adopted, as in the basilicas of Saint Peter, Saint John Lateran, and San Lorenzo.
Strict adherence to the custom was later made impracticable by the directions of city streets, although there is a Catholic church in Belfast, Ireland, twice as broad as it is long, to conform to the custom.
New Catholic Dictionary