Where To Cool Off In Rome, Italy
Capitoline Museum
Not only does the Capitoline Museum have air conditioning, it is a less frequented museum meaning you can have the AC unit all to yourself!
Vatican Museums' Sistine Chapel and Carriage Museum
The sistine chapel is nicely air conditioned, but you have to walk through some pretty warm exhibits before you arrive there as most of the museums are not air conditioned.
The carriage museum is tucked away around the corner and it's underground, making it crowd-free and nicely cooled.
Borghese Gallery
The Borghese Gallery is air conditioned and has restricted entry and exit times, so it never gets too full.
Public Water Fountains
There are roughly 2500 public water fountains throughout the city that supply free COLD water directly from the mountain springs. It makes for a great place to refill water bottles as well as splash cool water over your arms and face.