The largest church in the world is dominated by Michelangelo's imposing dome. It was originally built in 324 A.D. by Constantine, but completely rebuilt in the 16th century. Tradition states that the altar is placed directly over the burial place of St. Peter, the first Catholic pope. No matter what your expectations, it is safe to say that the church will exceed them. There are too many masterpieces to note, let alone mention. Of course, Michelangelo's Pieta and Bernini's Baldacchino, which is suspended above the altar, are the most noteworthy. The throne that St. Peter himself is said to have used is on display in an apse prepared especially for that purpose (although the chair itself dates from no earlier than medieval times). Of course, the entire basilica is dominated by Michelangelo's architecturally spectacular dome.
There are treasures beneath the church as well, and tours can be arranged to go below and see evidences of first century burial customs. The tombs of the popes are also available for viewing. If you would prefer to see the sights from a different perspective you can take the stairs to the top of the dome for an inspiring view of Rome.