Although it's a bit expensive and takes quite a while to take the cog rail trains to the top our visit to the Jungfraujoch was quite fun. The official railway website for Jungfraubahn is here and you can find out more with a google search. One of the many cool features is the extensive ice cavern. What you're seeing in the picture is the ice tunnel, which is solid ice: top, sides, and bottom. And it is very smooth and cold, I slid my shoulder on the wall for a while and my sweater didn't even get a bit damp.
Throughout the cavern they have nooks and crannies decorated with ice carvings and well lit sculptures. After wandering around for a while you walk up a set of steps and pop out on top of this glacier you've been walking inside of. Views are very impressive...especially if you like mountains and snow as much as I do.