Paris museums pass

Absolutey buy in Paris! You can purchase them at most places they are accepted at,, choose a less crowded museum so you don't have to wait in line to do so.
Where are you staying, if you tell we may be able to suggest the closest place to buy at. Some tabacs sell them too.. but thats hit and miss. No advantage to prepurchase, costs more and its one more thing to lose before you go!

Bea, I agree totally with Pat. You can purchase the Museum Pass at any Tourist Information (TI) center in Paris, so you can just ask your hotel where the nearest one is (Rick's Paris guidebook gives you some TI locations, I think). You can also buy them at any of the lesser crowded museums in Paris. I would avoid buying one at the Louver, however, as it is just too crowded.

I think there's a small museum in front of Notre Dame where you can buy a pass. It's down some stairs and most people walk right by it. Double check. See what is covered by the Pass and if it has some name like Archaeology Museum (maybe not the right name) and it's in front of or near Notre Dame, that's where I would go. I think I bought my pass there last time, but not 100% sure. I could only get my daughters together for 4 days at the same time and we traveled from Seattle, so I was pretty wiped out by all the things we crammed in. But, I can tell you that, even if you can only go for 4 days, Paris is worth it. And, never go without the pass...even if you only want to see Monet's waterlillies You'll stand in line for half your trip.

buy when you are there it's very easy--we picked them up at a tourist center of sorts -but there are plenty of places as the other posters said.. its not cheaper online and yes you don't have to worry about losing them.