Approach St. Peter's at dawn, when the sun tinges rooftops in the Borgo, the medieval neighborhood to the east. The Catholic Church's center and the world's smallest nation (108.7 acres, pop. 821), Vatican City is separated from Rome itself by ninth-century walls. At this hour, broad Via della Conciliazione, the pedestrian thoroughfare to St. Peter's, is not yet tourist-soaked. St. Peter's Square itself may be empty, except for the occasional, hurrying black-robed figure. Let the scale of the place overwhelm you: the two sweeping semicircles of Bernini's four-tiered colonnade and, at the piazza's center, the Egyptian obelisk older than Rome itself. Even if you're the most avowed atheist, your eyes can't help but follow the lines of Michelangelo's 448-foot-high dome toward Heaven. You have not yet entered St. Peter's Basilica, the vastness of which dizzies perceptions even morebut you have already stepped into 2,000 years of history and mystery.