With 42 themed areas, these gardens are a tranquil oasis amid urban congestion. From early spring to the first hard frost, rose, lilac, peony, iris and daylily gardens attract birds and butterflies. The Rock Alpine Garden mimics high-altitude life zones. The soaring glass dome of Boettcher Memorial Conservatory shelters tropical plants in a startlingly humid environment. Gentle paths meander through this paradise, best viewed from a platform suspended 40ft in an artificial banyan tree.