All Souls Church, Unitarian is a Unitarian Universalist church located at 1500 Harvard Street NW at the intersection of 16th Street, Washington, D.C., roughly where the Mt. Pleasant, Columbia Heights, and Adams Morgan neighborhoods of the city meet. The design of its current building, completed in 1924, is based on St. Martin's-in-the-Fields in London. It was listed on the National Register of Historic Places in 2020. All Souls, a member of the Unitarian Universalist Association of Congregations, describes its theology as having evolved from a liberal Christian tradition into a "rich pluralism."