7. Vatican Museums and Galleries (Musei Vaticani) Vatican City
mv.vatican.va
It's hard to overstate the cultural significance of this complex of museums, nestled in a tiny walled city in the northwest corner of Rome. You're not just looking at great art; You're looking at great art in its original setting, surrounded by the historical context that inspired it, which happens to be the heartbeat of the oldest Christian denomination in existence.
As you might expect with a museum so important, the staff run a very tight ship. During your sojourn around Vatican City, you may well see guards armed with automatic weapons, so behave. One look at the restored Sistine Chapel ceiling will make the trip worthwhile.