William H. Allen (1858–1936) was an American architect who worked in New Haven, Connecticut.
[1] Allen, a native of Northampton, Massachusetts, moved to New Haven around 1867 or 1868 and spent most of his adult life there.
[1] He and Richard Williams' Beaux Arts architecture design for the New Haven County Courthouse won a design competition over submissions from several well-known architects.
[2] [3] Several of his works are individually listed on the U.S. National Register of Historic Places (NRHP).
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