We recently found out about Andy Goldsworthy's Woodline installation in the southeast corner of the Presidio by the Arguello Gate, just east of Lovers Lane. The artist used reclaimed trees to make a long meandering serpentine structure that winds it's way down the hill for about 2/3rds the distance of lovers lane. It's set amongst a forest of eucalyptus trees bathing your hike in a wonderful diffused light, great for photos.