The IRS says that 529 funds can be used at any Eligible Educational Institution, defined this way (from IRS Pub. 970):
An eligible educational institution is any college, university, vocational school, or other postsecondary educational institution eligible to participate in a student aid program administered by the U.S. Department of Education. It includes virtually all accredited public, nonprofit, and proprietary (privately owned profit-making) postsecondary institutions. An eligible educational institution also includes certain educational institutions located outside the United States that are eligible to participate in a student aid program administered by the U.S. Department of Education. The educational institution should be able to tell you if it is an eligible educational institution.