Botanical gardens are more than the sum of their flora. Originally cultivated with medicinal herbs in mind, classical botanical gardens soon hosted flowers and trees from around the world to study, educate, and offer an aesthetically-pleasing place for visitors. More recently, research gardens have expanded their missions to include conservation – meaning your entry fee is helping to maintain world biodiversity. "Most of these gardens are curated and displayed like museum objects in a way that paintings are displayed in an art museum," says Morris Arboretum's executive director Paul W. Meyer. "And these collections double as conservation repositories." We consulted Meyer and Katy Moss Warner, head of the American Horticultural Society, to find exemplary botanical gardens from around the world that are worth traveling to see.