Fontainebleau

Less than an hour outside Paris, this tidy suburb is great for hiking and biking. Rent a bike at À la Petite Reine and ride through the forest, which stays cool in the summer because of all the trees. People have been rock-climbing here since the 19th century, and you can usually find a range of hiking trails from kid-friendly to difficult. Be sure to tour the magnificent medieval castle, once home to many French kings and the set location for movies like The Three Musketeers. The grand horseshoe-shaped stairway at the entrance is legendary.