I've just spoken with a contact I have on CERN. Every summer, the they host these summer studentships.
The experience was described to me as it follows (literally):
The requirements are all there, on the summer studentship page. See if you comply with all of them, and if so, submit your candidature!Get lectures from amazing people during the morning, work a little (not too hard) on an interesting project during evenings, and party a lot at night.
The nice touch is that I happen to know that on this particular year they need at least one person able to defend himself with Python. If that's your case, you have a little competitive advantage.
This is an amazing opportunity, you should give it a try. But you have to be fast, the submission date limit is January the 31st!