In early Christian churches the narthex was often divided into two distinct parts: an esonarthex (inner narthex) between the west wall and the body of the church proper, separated from the nave and aisles by a wall, arcade, colonnade, screen, or rail, and an external closed space, the exonarthex (outer narthex), a court in front of the church facade delimited on all sides by a colonnade as in the first St. Peter's Basilica in Rome or in the Basilica of Sant'Ambrogio in Milan. The exonarthex may have been either open or enclosed with a door leading to the outside, as in the Byzantine Chora Church.