As you drive into Boulder on U.S. Highway 36, the backdrop of the Rockies resembles a postcard of the Alps. Drive up Flagstaff Road, park your car, and walk a few yards to picnic tables amid the trees. After lunch, take every scrap with you. Littering is illegal everywhere in the States, but in Boulder it's also considered a sin.
17. Native History - Southwestern Montana
Head north, to Big Hole National Battlefield, on State Route 43. This site commemorates an event in U.S. history that's tempting to forget: the brutal treatment of the Nez Perce-the very people who helped Lewis and Clark on their expedition of discovery. The Park Service charges no admission to this site, which re-creates the Nez Perce village on the Big Hole River that was attacked at dawn on August 9, 1877.
18. Shopping Experience - Seattle
Downtown's Pike Place Market claims to be the nation's oldest continuously running farmers' market. Don't miss the fishmongers tossing salmon and other "flying" fish to clerks at the counter. You have to pay for your fish, of course, but not to see this cheerful ritual played out all day long.
19. Tree Gazing - Humboldt County, California
Don't miss a glimpse of the very tall trees in Redwood National Park on California's northern coast (Hyperion is the world's tallest, at 379 feet). These redwood ecosystems, which constitute America's rain forests, are hard to traverse but worth the effort.
20. Seals and Swimming - San Diego
At the southern end of the Golden State, in the village of La Jolla, you'll find a small, sandy cove called the Children's Pool. Its dilapidated seawall, constructed in the 1930s, still provides protection for swimmers, although recently it's been taken over by seals and sea lions who come here to rest. A court battle rages over whom the beach rightfully belongs to-people or seals-but regardless of who wins, both the water and creature watching are exhilarating.
21. Red Rock Climbing - Sedona, Arizona
Sedona's Coconino National Forest includes the famous red-rock formations Cathedral Rock and Bell Rock. Entry to the forest is free, but you'll pay $5 a day to leave your car. A few miles away, visit the Chapel of the Holy Cross. Designed by Marguerite Brunswig Staude, a student of Frank Lloyd Wright's, the modern structure complements the surrounding buttes and big blue skies.
22. Siege Site - San Antonio
Remember the Alamo? You will after visiting San Antonio and learning about its watershed moment in 1836. The rebels who defended this place died-but, spurred by the famous battle cry, the revolutionaries later won their fight for independence against a much larger Mexican army. The former mission and fort defended during the 13-day siege is now a museum.
23. Diamond discovery - Murfreesboro, Arkansas
This town claims the world's only public diamond mine. At Crater of Diamonds State Park, visitors can dig for the precious gems themselves. Since the first diamonds were discovered here, in 1906, more than 75,000 have been found. Entrance to the park is free, but digging costs $6.50 for teens and adults and $3.50 for kids. You keep any gems you unearth.
24. Music Appreciation - New Orleans