When artist Harrell Fletcher came to the Exploratorium at Pier 15, he wondered what would happen if he went straight to the back—and just kept going. He and a group of Exploratorium staff decided to find out: over the course of four days, they walked east from Pier 15 to the summit of Mount Diablo, about 40 miles away, taking part in a variety of scientific and historical experiences along the way. Join the trip here.