The architect conceived a plan of two churches, one above the other, and interconnected the lower or crypt on the level of the former churches, and the upper church. The lower preserves the Holy Grottos and the remains of the Byzantine and Crusader churches, which bespeak an uninterrupted cult and authentic tradition. The roof opens in a star like lantern in the centre of the upper church to which there is access by stairway. The upper Church is the Latin Parish Church of Nazareth. The central feature was to be the Grotto marked on high by the striking dome. The Dome of the Basilica is an upside down lily (32 leaves and a continuing M from Maria).
The mosaic apse is made by Salvatore Fiume (died Milan 3 June 1997), representing the "one, holy, catholic and apostolic church" (Triumph of the church).
On all the walls of the upper Church, as well as in the atrium surrounding the Church paintings, sculptures, bass-relief represent the Marian Sanctuaries of the world, donated by Christian communities around the world.
The middle of this church enshrines the most sacred spot of all, the Grotto, and here the roof of the lower church is pierced by a star-shaped oculus situated exactly under the dome of the upper church. The entrances to the church are from the portico on the west side, in line with the whole building, and from the south in the direction of the Grotto. The side entrances in the main facade give access to two spiral stairways leading to the upper church.
However, the real main entrance is to the North. Here, on a level with the upper church, is a large elevated square of 800 square meters. Thence, two doors open into the church proper while, in line with these, there is a small eight-sided shrine, which is the baptistery. The great elevated square also serves another purpose: to protect the remains of ancient Nazareth's dwellings which have been excavated in the soil below.