Old Man House, Historic building in Washington, US.

The Old Man House was a winter longhouse on the shore of Agate Pass, just south of present-day Suquamish. It measured between 600 and 1,000 feet long, making it the largest longhouse on Puget Sound. The site is now a grassy lawn with a small single-storey building with horizontal wooden siding, a low-pitched shingled roof and a single dark door.

The village site at dxʷsəq̓ʷəb was occupied for at least 2,000 years, and the longhouse, between 600 and 1,000 feet long, was probably raised in the late 18th or early 19th century. After the 1855 Point Elliott Treaty the land became the Port Madison Indian Reservation. In 1870, after Chief Seattle's death, agent William DeShaw had the house burned to force the Suquamish into single-family homes; they rebuilt anyway and DeShaw resigned.

The Lushootseed name of the site, dxʷsəq̓ʷəb, means "clear salt water" and is the source of the name Suquamish, "people of the clear salt water." The English name comes from Chinook Jargon: "oleman" means old or from the old times, and "house" meant any building. The site is now a park returned to the Suquamish Tribe in 2004.

The site is an acre of waterfront lawn on Agate Pass, just south of Suquamish; the longhouse itself no longer stands. The park was returned to the Suquamish Tribe in 2004, so check tribal visitor information for access and timing before you go.

The longhouse was burned in 1870 on the orders of William DeShaw, the reservation's Indian agent and a friend of Chief Seattle, to push the Suquamish into single-family homes. The Suquamish rebuilt their village on the same spot, and DeShaw resigned from the Bureau of Indian Affairs.