I mean, literally: how cool is the Large Hadron Collider?
Now you can find out. The LHC page has a map showing the temperatures of various aspects of the giant collider. As I write this, sectors 7-8 and 8-1 are the warmest at a balmy 20 - 60. But that's not Fahrenheit, or even Celsius: it's Kelvin, baby, and that's cold. 60 Kelvin is -213 Celsius, and -350 F. Yikes.
But it'll get colder still. Soon the whole ring will be chilled to operating temperatures, and then away we go, smacking protons together at a whisper slower than light itself. What new physics will they find?