Gardens of Montjuïc, Barcelona
Concierge.com's insider take:
This headland park to the southwest of the city welcomes more than 15 million visitors a year to its museums, concert arenas, sports centers, and gardens (only New York City's Central Park gets more foot traffic). Mossén Costa i Llobera is the best collection of its kind in Europe—a secret garden with a sea view, planted with more than 800 exotic species of cacti (Carretera de Miramar 1; 34-93-424-3809; www.bcn.es/parcsijardins/pa_llobera.htm). The Jardí Botànic, with its futuristic steel banks and hardwood walkways, was inaugurated in 1999. The planting pulls together vegetation from Mediterranean-like climates around the world, such as rapistrum rugosum—Texan bastard cabbage (34-93-289-0611; www.bcn.es/parcsijardins/pa_botanic.htm). Full maturation is still a ways off, but for keen gardeners and botanists, it's a fascinating amble.