It is based on the Basilicas of the Greek and Roman cultures. The Early Christian Churches adapted the Greek and Roman design to suit their religious needs. They took the original rectangular plan and changed it to look like the Holy Cross by adding a transept. This is seen in the Early Christian Church of St. Apollinare, in Ravenna Italy. They added an atrium in front of the entrance to the church.
The church still has columns, but they were on the inside, lining the nave, where the worshipers stood and today we sit. There were nine columns total. Walkways were on the sides of the colonnades, and they were called aisles. The Basilica’s emphasis was horizontal. When people entered they were supposed to look at the far end of the church, toward the apse or altar. Under the apse was a crypt or burial chamber where they kept the dead.
Church decoration was an intricate part of the message and meaning of the structure. The church had to be impressive not only in size, but in beauty. The outside of the church was left plain, to symbolize the earthly world, or normal life. The inside was richly decorated with gold, silver, semi precious stones, and art. The typical art forms were mosaics, painting, and sculpture. These included depictions of Jesus, the Holy Cross, the Holy Circle which symbolized Heaven, and other religious attributes.
All of this was to show the splendor of God and Heaven. One of the aspects the two plans have in common is symbolic representation. They tried to convey biblical messages through art. The Rotunda plan church of Santa Costanza is not much different.
The emphasis of the church was not at the far end, because there was no real far end. The emphasis was vertical. People were supposed to look upward at the ceiling toward God in Heaven. The ceiling was decorated with a mosaic, which again depicted religious scenes.
Because the church was circular the altar was in the center. Around the center were twelve columns, possibly symbolizing the twelve decipels. Around that was the ambulatory or walkway, similar to the aisles in the Basilica plan. The Rotunda was also plain on the outside and rich and colorful on the inside, once again depicting the beauty of the Christian Religion.
The church retained most of the aspects of the Basilica plan. One of the main connections between the two designs is the fact that the purpose of these churches is that they are places of worship. While they have many similarities, they are also their own unique design with a personality of their own. The churches are designed according to the religious demands of the time. Religion shapes the way in which churches are built.