Things to Do in Paris

Cycle

Try cycling the Parisian streets. With its myriad alleys and bike trails, Paris is an ideal place to visit on two wheels. Begin in the heart of town, near Rivoli, and make your way by bike to Versailles and back---about 22 miles---or follow the Seine 10 or 20 miles for a hearty, morning ride. The truth is, your bike path through the city is absolutely customizable, since so much of Paris is bike-friendly. Bike rental shops are available throughout the city.
Paris Bike Company
56, Rue Gallieni
92240 Malakoff, France
011 (+33) 0953 358477‎
parisbikeco.com

Trek

Few cities in the world can match Paris in terms of cultural richness. Consider mixing this with your love of the outdoors by heading out on a major trek---across and around France's capital city. You can grab a map and trace your route yourself, noting the city's vast offerings in the form of architectural wonders, gardens, monuments, museums, parks or culinary hot spots---or join a walking tour, of which there are many in the city. Either way, you're liable to get a good workout and see the city at the same time, without ever having to get in a taxi or a bus.
Classic Walks of Paris
24, Rue Edgar Faure
75015 Paris, France
011 (+33) 0156 581054‎

Explore

For the truly adventurous, there is the option of going underground---and that's not a metaphor. In fact, underneath the city of Paris lies over 177 miles of tunnel. Much of this dark, interconnected system has been used by artists and others as their own personal canvas, and as such art and poetry---both contemporary and far more aged---is splashed across its walls. You'll turn a harrowing corner and come face to face with a line of sculpted gargoyles. Another bend may lead to a wall of skulls many centuries old. The key here is to descend into the caves with a guide; getting lost down here could lead to a number of undesirable ends.
Paris Sewer Museum (with tours)
Quai d'Orsay
75007 Paris, France
011 (+33) 4705 1029
europeforvisitors.com