Tulsa is the second-largest city in the state of Oklahoma and the 47th-most populous city in the United States. It is located along the Arkansas River at the foothills of the Ozark Mountains in northeast Oklahoma, a region of the state known as “Green Country.” The city has been called one of America’s "Most Livable Large Cities" by Partners for Livable Communities, Forbes, and Relocate America. In addition, Tulsa was ranked among the top 50 best cities in the United States by BusinessWeek. The city of Tulsa manages 135 parks that are spread over 6,000 acres, making any outdoorsman feel at home. For connoisseurs of the arts, Tulsa has several permanent dance, theater, and concert groups such as the Tulsa Ballet, the Tulsa Opera, and the Tulsa Symphony Orchestra. Other points of interest include the Tulsa Zoo, the Oklahoma Aquarium, and the Tulsa Convention Center.