Definitely worth a visit:
1. The Dome and the Oculus: The largest non-reinforced concrete dome in human history. The interior height equals the dome diameter, both being 43.3 meters, perfectly accommodating a complete sphere. The only light source is a 9-meter-high circular opening at the top, allowing sunlight to slowly move across the ground over time. Rainwater is collected through hidden drainage holes in the floor, preventing water accumulation. Michelangelo described it as "the design of angels."
2. Raphael's Tomb: Located on the left side of the hall, Raphael, the Renaissance master, is buried here. His epitaph is deeply moving: "When he was alive, nature feared to be conquered by him; when he died, nature feared to perish with him." A major attraction for art lovers. Also located here are the tombs of Italian kings.
3. The Portico Columns: The entrance features 16 massive granite columns, quarried from Egypt and transported to Rome. Each column weighs over ten tons and is 2000 years old. The heavy bronze doors are also original Roman artifacts.
4. History: Completed in 126 AD during Hadrian's time, it was originally dedicated to all the Roman gods. It was converted into a church in the 7th century, which is why it was preserved intact and did not have its stones removed like other ancient sites.