La Grande Mosquee
Paris is a cosmopolitan city. Despite the uniformed style buildings of the Haussmannien Era, you may also find other great architectural designs from all over the world, from a sino-japanese pagoda to a muslim mosque.
La Grande Mosquee is one of the greatest examples. Built in the mid 20's to thank the Muslims people who helped fight with the Germans in the World War I. Most of the spaces can be visited on a guided tour except for the praying room, of course.
The main draws, however are the sumptuously decorated tearoom and its Hamman where you can relax in a sauna and then be treated with a gommage- a body scrub and an oil massage.
Personally, I always go there for tea, either outdoors under the shades of the fig tree or indoor under the rich ambience. You will never believe that you really are still in Paris.

