The University of Pennsylvania (commonly referred to as Penn or UPenn) is an American private Ivy League research university located in Philadelphia, Pennsylvania, United States. Penn considers itself the fourth-oldest institution of higher education in the United States,[note 2] as well as the first university in the United States with both undergraduate and graduate studies. It is also one of the Colonial Colleges. Incorporated as The Trustees of the University of Pennsylvania, Penn is one of 14 founding members of the Association of American Universities.