Few art museums are truly worth braving massive crowds, pushy tourists, and long lines. The Musei Vaticani is one of them, and is a must-see on even the shortest Roman journey.
Begin your visit by arriving before or shortly after the doors open at 8:45am, every day except Sunday. (Be prepared to wait in line outside for up to an hour. The line, though long, moves quickly.) Pay your entrance fee of 6 euros and head inside.
Many guidebooks contain excellent walking tours of the museum's many rooms. If yours is somewhat lacking, buy the audio tour in your language of choice. We used Rick Steve's Rome, which was informative and helpful.
The highlight of the museum is the many works of Renaissance art by masters such as Raphael, Michelangelo, and da Vinci. Don't miss the Raphael rooms, with the magnificent School of Athens, a sort of "Where's Waldo" of Renaissance Italy.
Plan at least 30 minutes for the world-famous Sistine Chapel. Michaelangelo's masterwork is breathtaking and stunning, far more than can ever be conveyed in a book or on a slide.
Photos are not allowed in the Sistine Chapel. Elsewhere, bring high-speed film to photograph the works of art without a flash.
Don't miss the Laocoon and Bernini's David for excellent sculpture.