"The Victorian-era glass and wood structure, which looks like a sugar-coated castle atop a grassy slope, is Golden Gate Park's oldest building. It's also one of San Francisco's most splendid historic sites. Wander through five different galleries housing 1,700 species of aquatic and tropical plants along with the world's largest public collection of high-altitude orchids. The potted plant gallery featuresrare flowering plants and an assortment of decorative urns and containers from all over the world, including a leftover from San Francisco's 1915 Panama-Pacific International Exposition. Keep your eyes open for special exhibits, including the annual Butterflies and Blooms , whichtransforms the conservatory into a magical garden aflutter with hundreds of butterflies."