The Dubois-Sarles Octagon is an octagon house located on South Street in Marlboro, New York, United States. It was listed on the National Register of Historic Places in 2002.First built around 1850 by the Dubois family, it was renovated in 1872 by the Sarleses. As a result it reflects two different architectural styles: Italianate and Second Empire. Unlike most other American octagon houses of the period, its interior follows a sidehall plan, rather than the radial center plan advocated by Orson Squire Fowler.BuildingThe two-story house sits on a stone foundation. It is sided in asphalt, with overhanging bracketed eaves and a decorated frieze at the roofline. Above it is the mansard roof, covered in fish-scale slate shingles.The main entry is located at the southeast facet of the house. Unusually for an octagon house, it is recessed to create a porch, extending outside of the house, overlooking the Hudson River roughly a mile to the east. A two-story rectangular kitchen wing projects from the west facet, with a sympathetic contemporary octagonal hip-roofed porch wing attached to it. The remains of an earlier porch project from the east facet.