Participants in WalkingTown DC 2010 stroll around Lincoln's Cottage in Northwest.

You’d better pace yourself. WalkingTown DC/BikingTown DC, a smorgasbord of free tours all over the District orchestrated by Cultural Tourism DC, has expanded from a weekend to nine days. Between 9 a.m. Saturday and 5 p.m. Oct. 2, there will be nearly 200 chances to stretch your legs in all eight wards.

That means there are exponentially more opportunities to get a move on — including excursions at lunch and after work during the week. The program schedule helpfully includes the fitness level for each tour, because they range in distance from two floors of the National Museum of American Jewish Military History (Mon., at noon) to four miles around the National Arboretum (Sat. at 10 a.m.).

The dozen biking tours cover more ground — up to 15 miles — but they’re also scaled by difficulty. Even folks who haven’t hopped onto a saddle in years can handle the new two-mile Edgewood Murals tour (11 a.m. Sat. and Sun., and Oct. 1 and 2). And they can make sure their bikes are up to the task at several bike clinics that have partnered with the program. (See site for details.)

Don’t think walking counts as exercise? Try doing several tours in a day and rushing between them on foot or bike, and you’ll easily rack up a 10K. But the mileage won’t feel exhausting, says coordinator Helen Gineris, because you’ll also be engaging your brain. “If you’re at the treadmill watching TV or reading, you want to use your mind while you’re working out. So why not learn about the culture of the city around you?” Gineris says. “D.C. becomes your gym for the duration of the tour.”

That’s the exact premise of another new tour this year, “Fitness Walk of D.C.’s Circles and Squares” (Sun. at 8:30 a.m. and Sept. 30 at 6 p.m.; it’s also the first dog-friendly tour offered through the program). Led by personal trainer George Kassouf, the tour is based on a route he first developed for a client purely as a path to fitness. “But then I thought this would be more interesting if I knew what I was looking at,” says Kassouf, who hit the history books.

Quirky facts will make your muscles forget they’re tired, he promises. At least, until the end of the four-mile tour.