The basilica is moreover interesting because its general plan resembles, very closely, the description given by Eusebius of Constantine's buildings over the Holy Sepulchre at Jerusalem. On the west was an atrium or outer court, parts of the outer walls of which and shafts of its columns still remain. A narrow vestibule or narthex, entered by a door scarcely four feet high, leads into the basilica itself, which consists of a nave and four aisles, with four rows of eleven columns each, a total breadth of about thirty yards, and a length about equal.
The aisles have flat roofs, above the pillars which are nineteen feet high, but the nave has a clerestory, with walls some thirty feet high above the capitals, and a pointed roof. A wall has been built across the east end of the basilica, separating off the chancel, which has three apses, north, south and east, and which forms the Greek church. Beneath the chancel is the Grotto of the Nativity. North of the basilica is the more modern Latin chapel of St. Catherine, from which a staircase leads down to vaults communicating with the grotto.
The pillar shafts are monoliths of red and white marble, painted with figures of saints, now dim with age, and scrawled over with the crests and titles of knightly pilgrims of the Crusading ages. The capitals are of the Corinthian order, debased in style, with the cross carved on the rosettes of each. The wall above was once decorated all over with glass mosaic, fragments of which still remain, representing scenes in our Lord's life, portraits of angels and of Scripture characters, with arabesques and Greek inscriptions. These mosaics, with those on the chancel walls, were executed by order of the Greek Emperor, Manuel Comnenos, in the middle of the twelfth century. The roof above, once painted and gilded, was put up in 1482, the fine rafters having been given by Philip of Burgundy, the lead (stripped off later by the Moslems to make bullets) by Edward IV. of England; and the work was executed in Venice, and brought on camels from Jaffa. Further restorations were made in 1478, and again in 1672 and 1842, but the majority of the work appears to belong to the original structure of the time of Constantine.