Dubbed the Old Pueblo, Tucson is a fast-growing city known as much for its metropolitan sophistication as for its unique blend of cultures. Vast deserts, green canyons and majestic mountain ranges form an impressive backdrop, and close proximity to the Mexican border is evident in the architecture, distinctive cuisine, lively fiestas and the annual festivals. Tucson's mild, dry climate – blessed with year-round sun – makes it a popular winter resort. Visitors can take in attractions such as the Titan Missile Museum, Biosphere 2, Reid Park Zoo, Kitt Peak Observatory and several national parks. Economically, the city is driven by electronics and missile production, and is recognized as both the premier health services center of the Southwest and the astronomy center of the world.