The W.P. Mills House, also known as Cushing House, Longenbaugh House, Poulson House and Island House, is a historic house at 1 Maksoutoff Street in Sitka, Alaska. It occupies a prominent site in Sitka, located on a small island in the harbor at the end of a 400-foot (120 m) causeway. The house is located on the site where, during the Russian period in the early nineteenth century, a fish-packing operation was located. In 1915, W. P. Mills, son of one of the former American owners of the saltery after the Alaska Purchase, hired Seattle-based architect Louis L. Mendal to design a house to stand on the old saltery's foundation. The design, which used the foundation as well as the massive wooden door of the saltery, adapted the foundation to provide a sheltered and private courtyard space, and to take advantage of the expansive views available.