It's a fairly long haul from the nearest major city, but if you've got the extra time, it's well worth the trip. Nestled in the Southwest corner of Colorado, Mesa Verde National Park is one of our nation's oldest man-made treasures. Built by the Pueblo people over 700 years — from 600 to 1,300 — the park boasts nearly 5,000 architectural sites, including 600 cliff dwellings. As you might imagine, it'll require some walking, climbing, and at times even crawling to see them — they are on cliffs, after all — but the views and perspective gained are well worth the effort.