The magnificent Pantheon, built by the Romans as a temple to all of their gods, is the Eternal City's best-preserved monument. Engineers still admire how such a mathematically precise structure was built without modern technology. Standing under the massive solemn dome, you'll gain a new appreciation for the grandeur that was — and still is — Rome. For more information on the Rick Steves' Europe TV series — including episode descriptions, scripts, participating stations, travel information on destinations and more — visit www.ricksteves.com.