Tucson, Arizona is home to the nation's largest cacti. The giant saguaro is the universal symbol of the American west. These majestic plants, found only in a small portion of the United States, are protected by Saguaro National Park, to the east and west of the modern city of Tucson. Here you have a chance to see these enormous cacti, silhouetted by the beauty of a magnificent desert sunset.

...Excerpt from NPS website