Final answer:
The Basilica of St. Paul Outside the Walls is a massive church with brick exterior and magnificent mosaics inside. It has an apsidal plan, with a raised central floor and a double surround of columns.
Step-by-step explanation:
The Basilica of St. Paul Outside the Walls is a massive church with an overall length of 169 meters and an interior nave that is 25 meters wide. The exterior of the church is made of brick and the walls are pierced with many windows. The interior is covered with magnificent mosaics from the early Medieval period.
It is apsidal at both ends and has a raised central floor. The main hall has a double surround of columns, totaling 96 columns. The bricks used in the construction were taken from ancient Roman buildings and reused in the 6th century.