Final answer:
The eastern orientation of the apse in Catholic churches is rooted in religious symbolism, aligning with the direction of the rising sun, Jerusalem, and emphasizing interior space. The basilica form was chosen for its symbolic and practical function for worship and accommodating pilgrims.
Step-by-step explanation:
The tradition of building Catholic churches with the apse on the eastern end comes from the principle of orienting the church towards the rising sun. This practice symbolizes the resurrection of Christ and the hope of his second coming. The apse, which typically holds the altar and the Eucharist, faces East to represent the direction from which Christ ascended and where he is expected to return during the Second Coming.
This tradition can be traced back to the early Christian period when Christians modified the design of the Roman basilica. They added a transept to give the building a cruciform shape, symbolizing the Crucifixion. The addition of a transept, along with the placement of the apse on the eastern end, became a common feature of Catholic church architecture.