Longwood
Natchez, Mississippi

Longwood, the largest octagonal house in the United States, is an historic antebellum mansion located in Natchez, Mississippi. The mansion is known for its octagonal design, byzantine onion-shaped dome and the contrast between the finished first floor and the unfinished upper floors. Longwood is on the U.S. National Register of Historic Places and is a National Historic Landmark.

Longwood, also known as Nutt's Folly, was designed in 1859 by Philadelphia architect Samuel Sloan for cotton planter Dr. Haller Nutt and and his wife Julia. Construction began in 1860 but was halted in 1861 by rising tensions over the Civil War. Craftsmen, who were from the northeast, dropped their tools (where they still lay) and fled home. The exterior was mostly complete but the home's interior was left unfinished except for the lower level.

Haller died of pneumonia in 1864 and his Julia and children continued to live in the finished first floor. The interior of the upper five stories were never completed. The property was deeded to the Pilgrimage Garden Club in 1970 and designated a National Historic Landmark in 1971.