San Francisco is awash in quirky attractions, but one unusual landmark serves as a window into the 15th century as well. The Camera Obscura and Holographic Gallery is located outside the Cliff House restaurant in Ocean Beach, and it's essentially a walk-in camera based on photographic principles first outlined by Leonardo da Vinci. Perched on the edge of a cliff, visitors enjoy a live image of the beach and surrounding ocean as captured by a sophisticated rotating lens, while all around them are 3-D holograms that add an otherworldly aura to the darkened room. Built in 1949 to be part of the Playland at the Beach amusement park, the Camera Obscura was moved to its current location when the park closed in 1972, and it now represents the last living reminder of the storied history of the area. Visitors often combine a visit to the Camera with a meal at the historic restaurant, which dates back to 1858, when its first incarnation was built with logs salvaged from a wrecked ship. Destroyed and rebuilt several times over the years, it's now part of the Golden Gate National Recreation Area and operated by the National Park Service. Starwood has hotels throughout the San Francisco area, including the Sheraton Fisherman's Wharf Hotel, just 15 minutes away.

[image via gocalifornia.about.com]