The Papal Basilica of St. Paul outside the Walls (Basilica Papale di San Paolo fuori le Mura), is one of Rome's four ancient major basilicas. The Basilica was founded by the Roman Emperor Constantine I over the burial place of St. Paul, where it was said that, after the Apostle's execution, his followers erected a memorial, called a cella memoriae.
In 386, Emperor Theodosius I began erecting a much larger and more beautiful basilica with a nave and four aisles with a transept; the work including the mosaics was not completed until Leo I's pontificate (440–461). Under Pope St. Gregory the Great (590–604) the Basilica was extensively modified. The pavement was raised to place the altar directly over St. Paul's tomb. A confession permitted access to the Apostle's sepulcher.
As it lay outside the Aurelian Walls, the Basilica was damaged in the 9th century during a Saracen raid. Consequently, Pope John VIII (872–82) fortified the Basilica, the monastery, and the dwellings of the peasantry, forming the town of Joannispolis. It existed until 1348, when an earthquake totally destroyed it.
The graceful cloister of the monastery was erected between 1220 and 1241.
On 15 July 1823, a negligent workman repairing the lead of the roof, started a fire that led to the near total destruction of this basilica, which, alone among all the churches of Rome, had preserved its primitive character for 1435 years. It was re-opened in 1840, and reconsecrated in 1855 with the presence of Pope Pius IX and fifty cardinals. The complete decoration and reconstruction, in charge of Luigi Poletti, took longer, however, and many countries made their contributions. The Viceroy of Egypt sent pillars of alabaster, the Emperor of Russia the precious malachite and lapis lazuli of the tabernacle. The work on the principal façade, looking toward the Tiber, was completed by the Italian Government, which declared the church a national monument.
References:The Walls of Constantinople are a series of defensive stone walls that have surrounded and protected the city of Constantinople (today Istanbul) since its founding as the new capital of the Roman Empire by Constantine the Great. With numerous additions and modifications during their history, they were the last great fortification system of antiquity, and one of the most complex and elaborate systems ever built. They were also the largest and strongest fortification in both the ancient and medieval world.
Initially built by Constantine the Great, the walls surrounded the new city on all sides, protecting it against attack from both sea and land. As the city grew, the famous double line of the Theodosian Walls was built in the 5th century. Although the other sections of the walls were less elaborate, they were, when well-manned, almost impregnable for any medieval besieger.