The Wagner Free Institute of Science is a natural history museum at 1700 West Montgomery Avenue in north Philadelphia, Pennsylvania, United States. Founded in 1855, it is a rare surviving example of a Victorian era scientific society, with a museum, research center, library, and educational facilities. Its buildings, developed between 1859 and 1901, present the collections of founder William Wagner in the style of the period, and have been designated a National Historic Landmark for their architecture and state of preservation.