The first Christians met for instruction and worship in private homes. Jewish Christians also continued attend sacrifices at the Temple in Jerusalem or meetings in their synagogues. After the destruction of the Temple and the expulsion of the Christian Jews from the synagogue, however, these options were no longer open. As the numbers of Christians grew, they purchased houses and transformed them into cultic meeting sites just like the members of other non-dominant religions in the empire did. The house church at Dura Europas is a stunning example of this kind of worship facility.

With the conversion of Constantine and the continued success of Christianity, the numbers of Christians soon demanded new, larger structures for worship. Christians primarily turned to the basilica in designing their new churches. Hellenistic temples were not a good model, since in the traditional pagan cults of the empire only the priests were allowed to entire the temples. They were, therefore, much too small for Christian needs. The basilica, on the other hand, was a large structure designed for the public transactions of court and business. The architectural form of the basilica was ideally suited for the public, urban worship of the Christian Church.

Basilicas were long, high, wide rooms. At the far end of the room was an apse, a semicircular area that served as a focal point and sound amplifier. When basilicas were used to hold court, the praetor or the prefect would sit in the curale chair under the center of the apse. The judges would sit to his right and left. A large table stood in front of them on which they would place the law code. In Christian basilicas the praetor's curale chair was replaced by the bishop's cathedra. The bishop would preside over the liturgy from the cathedra flanked not by judges but by the presbyters. The table with the law code became the altar with the gospel book.

Figure 1 shows the exterior of the sixth-century basilica of S. Apollinare in Classe, the port town just outside of Ravenna. To the front of a basilica normally stood an atrium, that is to say a courtyard surrounded by columns. Then there was a covered porch or antechamber called the narthex.

After passing through the narthex, the worshipper entered the nave, a great hall flanked on each side by one or two aisles. Large windows piercing the wall above the height of the aisle ceilings lit the nave. This part of the wall was called the clerestory. Figures 2-4 are sketches of what some of the basilicas in Rome itself probably looked like in Antiquity. Note the great open expanses dominated by the apses. Figure 2 is a sketch of the fourth-century Basilica of Constantine. Figure 3 is the fifth-century basilica of Santa Maria Maggiore. Note the bishop's throne (cathedra) behind the altar and the benches for the presbyters on either side of it. Figure 4 is the basilica of Saints Nereus and Achilleus. Note the grating underneath the altar for the confessio where the relics of the saints would rest.

The interiors of the basilicas were decorated with beautiful marbles, colorful mosaics and exquisitely worked coffered ceilings. Figure 5 shows the stunning effects created by all the colors and the stately architecture. It is an image of the nave of S. Apollinare Nuovo in Ravenna.

Figure 6 shows a close up of one of the walls in S. Apollinare Nuovo. Note the columns and arches that separate the nave from the aisle and the windows in the clerestory.

Figure 7 shows a close up of the decoration on one of the basilica's walls. The mosaic is of the port and city of Classe. Christian's understood their liturgy to be a public service of thanksgiving and supplication offered to the Deity on behalf of the entire city and the world.

Figure 8 shows well the way in which the apse dominated the entire space of the nave. Above the apse is an image of Christ flanked by the four beasts of the Apocalypse generally associated with the four canonical gospels. In the apse itself is a paradisiacal scene in the center of which stands the good shepherd St. Apollinaris surrounded by his flock. He is standing with his hands upraised in the traditional attitude of Christian prayer called the orans position. The bishop would stand just beneath this image in the same position while intoning the Great Thanksgiving (Eucharistic Prayer).