Join a guided tour of the Pantheon and explore the history of the best-preserved monument from Ancient Rome. Your guide will let you in on the engineering secrets that made this monument the only one of its size and age to have survived in tact from Roman times. Learn how the remains of many martyrs were removed from the Christian catacombs and placed in the Pantheon on the orders of Pope Boniface IV In 608. Marvel at the immense dome with a diameter of 43 meters, and its famous oculus that allows natural light to illuminate the beautiful interior.