An hour from the Danish capital city of Copenhagen, visitors at an unusual spiraling walkway, meant to both stand out and blend in with the surrounding forest, can soar 14 stories high, above the canopy of trees, to experience a rare view of nature. Seth Doane talked with Jesper Mathiesen, a former Danish Navy SEAL behind the project, called Camp Adventure, and with architect Tue Foged, whose team designed the unique observation tower.