The William and Mary LeDuc Historic Site is a nationally significant historic property that includes an architecturally outstanding house and outbuildings , and historic grounds. Its unaltered Gothic Revival architecture, and especially the design source, establish its national significance. William LeDuc, an attorney, entrepreneur and distinguished Civil War officer, served as U.S. Commissioner of Agriculture under President Rutherford B. Hayes. Mary LeDuc selected designs from Cottage Residences, a seminal volume first published in 1842 by noted architectural writer and landscape architect Andrew Jackson Downing, whose work dominated New York's Hudson River Valley. Following Downing's stylistic guidelines, the LeDucs produced a stunningly landscaped architectural gem in a young river town on the Minnesota prairie. The house survives virtually unaltered from its appearance when it was completed in 1865-66. In 1970 the site was listed on the National Register of Historic Places.