For those of you who love getting outside, you"re in luck! Today is Take a Hike Day, an activity the American Hiking Society says will make you happier as you enjoy the great outdoors. And what better way to take a hike than a walk near Lovers" Lane in San Francisco"s Presidio? The sinuous trail we see in today"s photo is called "Wood Line" and was designed by the environmental artist Andy Goldsworthy. By using felled eucalyptus trees, Goldsworthy intended this land art to eventually biodegrade and fade back into the forest floor. It"s one of four of his works within this national park that once served as a US military outpost.