Mur Mur
Mur Mur is the most underrated cult treasure of Europe. Mur is French for "wall," and Mur Mur is the only gym I can think of worthy of the name "Wall Wall." The first time I walked in I felt as though they had stacked two typical climbing gyms on top of each other. It's big, and it attracts some big dogs.
Mur Mur has four main branches: two near Paris (the Paris walls can be found in the suburbs of Pantin, accessible by Metro line 7, and Issy, accessible by line 12 or RER line C), one in Lyon, and one in Tours. They're all around 20 meters high, which seems like a whole freaking lot, especially when you're lead climbing. Also, in terms of wall space, they're about as big as your average Safeway, so even if it gets absurdly busy (and it does on Saturday afternoons), you can usually find a route to climb. If it's too hard or too easy then that's tough luck. Wait in line, because it's worth it. Actually, waiting in line might afford you the opportunity to witness the surfacing of the French societal subconscious. First, the belayer will take any excuse he gets to ignore your presence. This is the French sense of hauteur (or is it grandeur, I always forget). Also, you'll probably see two people on the wall right near each other - one on, say, a gnarly sloper route with a heel-hook crux and another on a crimpy overhang with lots of campusing and barn-doors. They will also mutually ignore each other, but what's worse, they'll reach for different holds (obviously, the one for a sloper, the other for a crimper) in the same vicinity. Their limbs will battle it out for supremacy until one of them either takes a nasty fall or asks his belayer for a break. The latter is considered backing down and will rarely be seen. Observing this practice in person will let you pass out of any college course on feudalism.
But I digress. The really important part of Mur Mur is its overall accessibility. For example, you have to be a member to climb, which will set you back about 20 euros, but they never make you pay the membership fee the first time. If you go in the middle of the afternoon (how could I possibly afford to do something like that?) it's dirt cheap; 6 euros entry. Compare that to any gym in the U.S. They're extremely helpful with everything - the first time I came I was a newbie in the French-speaking world and I no idea how to say carabiner, harness, lead climb, et cetera. They1 were very accomodating and showed me the ropes. Ouch! Speaking of ropes, you don't need your own to lead climb. They even replace the ropes at a rate that almost makes you feel safe climbing on them. The greatest and scariest part about the gym, though, is that you don't have to get certified or checked to belay or to lead. This makes it very easy for one to take one's peeps with him and teach them on spot how to do the nasty. This is prohibited in a lot of American gyms, and it makes sense that it would be. France, though, is free from such constraints as strict laws and people who give a damn.
Definitely the most important part about Mur Mur is the way the routes are set. This is a nuance that you only begin to pick up on after you've climbed for a bit and start to get better. You begin to recognize the difference between a route that's just an arm-haul with figurehead footholds and one that takes a combination of power, grace, and ingenuity. Mur Mur has a staggeringly high proportion of routes which, once finished, make you say to yourself, "it felt really great to use my body like that!"
1 By "they" I mean Aurélie. Not only is Aurélie a beutiful name, but the woman herself, who works at Mur Mur Pantin, is one of the most stunning women I've ever set eyes on. Aurélie, si jamais tu lis cela: après avoir jeté ce con avec qui tu passes ton temps si précieux, sortirais-tu avec moi, cet américain mignon?