An octagon house is a style of home with eight symmetrical outside walls, giving the house an octagonal floor plan instead of the more typical square or rectangular one. This design was a popular style of American architecture in the 1850s. It was thought to have many design advantages over the Victorian style homes that were also common during that time period.
Other features of octagon houses often include verandahs surrounding the entire structure, central spiral staircases, flat roofs, and cupolas. They are usually built of brick or wood, but concrete construction is also not uncommon. Octagon houses can vary in size — some are quite modest at just one story and have no architectural embellishments, while others contain up to four stories and 60 rooms, with extremely ornate external decoration.
The octagon house trend was started by Orson Squire Fowler, a phrenologist who thought the eight-sided floor plan would lead to better health because it allowed for more air flow and natural light. The shape of the house also helped the structure to retain heat better in cold months and stay cool longer in the summer. Another design advantage was that the octagonal design allowed for more interior floor space than the usual square plan. After Fowler published a book titled The Octagon House: A Home For All, or A New, Cheap, Convenient, and Superior Mode of Building in 1848, thousands of octagon houses popped up across the United States and Canada. Fowler was also a proponent of building the homes from concrete, the material his own octagon house was made from.
Although the eight-sided plan was very popular for a short period of time, the more conventional square and rectangular floor plans remained more practical for most people. There were flaws to the octagonal house design that led to its downfall. Most notably, some rooms could only be reached by going through other rooms or the outside verandah, instead of a through a typical indoor passage or hallway.
A large number of octagon buildings remain standing, in the United States in particular. Nearly 70 of them are listed on the National Register of Historic Places, and six of those are considered national historic landmarks. These include The Octagon House of Washington, D.C., where the Treaty of Ghent was signed, and Thomas Jefferson’s Poplar Forest plantation home in Virginia. In addition to homes, other common octagon structures include barns, churches, schools, and libraries.