In my whirlwind visit to Rome, my friend Carol and I took a bus tour that went to the Vatican Museums and Sistine Chapel in the morning and the catacombs in the afternoon.
Trying to see the Vatican Museums in one morning is an utter joke. Merely trying to get a good look at the bits you're whisked past on the way to the Sistine Chapel is equally impossible. The word "huge" doesn't begin to describe the museums' dimensions. There's amazing work in there collected from every continent and era; there's a masterpiece hidden in every corner. It would take a lifetime to truly absorb it all. And I really wonder what they keep behind closed doors, things too terrible or precious to give over to public viewing.
Unfortunately, the tour didn't allow for any restroom time between leaving the Chapel and getting back on the buses. And I desperately had to use the facilities. Carol wanted to mail some postcards there so they'd have the Vatican stamp, so I told her where I was going, and sprinted down the 3 or 4 levels to try to find a restroom.
The Vatican restroom was probably the cleanest public facility I've ever seen. Spotless. But there was an odd severity to it, from the polished marble walls down to the chilly, seatless toilets.