California is a popular tourist destination, and it has many attractions to offer. Napa is a four-letter word that refers to the Napa Valley, a wine-producing region in Northern California. San Diego Zoo is an eleven-letter word that refers to the world-famous San Diego Zoo, located in Balboa Park in San Diego, California. It is one of the largest zoos in the world and houses over 3, 700 animals of more than 650 species.