It is on the outskirts of Rome, and is one of the city's five most ancient churches. It is also a World Heritage Site
It is St Peter's Basilica's younger sister
You ought to know that the history of this site is half-way between violent, savage and a sense of honour. It was during Nero's reign and Christians suffered a relentless persecution. Among them was Saint Paul, martyr of the Gentiles, who was executed on the outskirts of the city of Rome. Years later, the emperor Constantine came to power, and with him religious recognition for Christians. It was this Emperor who decided to pay tribute to the fallen martyr, in the place, where his remains lay. That is why the second largest Catholic Church in the Empire, and also one of the oldest, after the Basilica of Saint Peter, was constructed over Saint Paul's tomb. The fact that it was outside the walls of ancient Rome was the reason for it being known as St. Paul Outside the Walls or St. Paul beyond the walls. You can visit the Martyr's tomb and walk around the beautiful, extensive park that surrounds it. You are on the outskirts of Rome and can see the ancient Roman ruins from there. But while you are walking remember that you are on one of the sites which changed the world: the early Catholic Church.