Samuel Sloan (March 7, 1815 – July 19, 1884) was a Philadelphia-based architect and best-selling author of architecture books in the mid-19th century.
 He specialized in Italianate villas and country houses, churches, and institutional buildings.
 His most famous building—the octagonal mansion "Longwood" in Natchez, Mississippi—is unfinished; construction was abandoned during the American Civil War.
Lancaster County Courthouse is a historic courthouse building located at Lancaster, Lancaster County, Pennsylvania.
 The original building was built between 1852 and 1855.
 The original building was designed by Philadelphia architect Samuel Sloan (1815–1884).
 The north wing was added between 1896 and 1898, and low flanking wings on either side of the exterior staircase were added in 1926-1927.
 These later additions were designed by Lancaster architects James H. Warner and C. Emlen Urban, respectively.
 It is an important example of the Romanesque Revival style.
The Hughes-Young House, most commonly known as Mistletoe Villa, is a historic house in Henderson, NC.
 The house is often cited for its ornate Victorian detail and architectural elements.
 The first house on the site was built for William H. Hughes and completed in 1855.
 From 1883 to 1885 the house was significantly redesigned and overbuilt on the previous foundation for Ike J. Young, Civil War Colonel and four-term mayor of Henderson.
 The design of the current house is attributed to the famed architect Samuel Sloan but that fact has not been officially documented.
Hamilton Family Estate is a set of nine historic homes located in the Spruce Hill neighborhood of Philadelphia, Pennsylvania.
 They were built between about 1853 and 1863, and are representative examples of the Italianate-style of architecture.
 They are commonly built of stucco and masonry, with porches and bracketed cornices.
 The houses at 400 S. 40th Street and 4000 and 4002 Pine Street are believed to have been designed by noted architect Samuel Sloan.
Drexel Development Historic District is a national historic district located in the University City neighborhood of Philadelphia, Pennsylvania.
 It encompasses 96 contributing rowhouses dated to the mid- to late-19th century.
 A number of the rowhouses were designed by noted architect Samuel Sloan.
 The architectural firm G. W. & W. D. Hewitt designed rowhouses for developer Anthony Joseph Drexel on the block bounded by Pine, new 39th, Baltimore, and 40th Streets.
 They are representative of a number of popular architectural styles including Second Empire, Italianate, and High Victorian.
Gray Gables, also known as the James S. Mitchell House, is a historic home located at Winton, Hertford County, North Carolina.
 It was designed by noted architect Samuel Sloan and built in 1899.
 It is a three-story, irregularly massed, Queen Anne style frame dwelling.
 It has a corner tower, a wraparound porch with turned posts and carved brackets, and a steeply pitched gable roof.
Longwood, also known as Nutt's Folly, is an historic antebellum octagonal mansion located at 140 Lower Woodville Road in Natchez, Mississippi, United States.
 The mansion is on the U.S. National Register of Historic Places, and is a National Historic Landmark.
 Longwood is the largest octagonal house in the United States.
Adolphus Gustavus Bauer (1858–1898) was an architect in North Carolina.
 He worked with the more famous architect Samuel Sloan and helped him build the Executive Mansion in Raleigh.
Highland Hall, also known as the Courthouse Annex, is a historic school building located at Hollidaysburg, Blair County, Pennsylvania.
 It was designed by noted Philadelphia architect Samuel Sloan (1815-1884) and built about 1865.
 It is a four-story, "T" shaped stone building measuring 150 feet wide and 160 feet deep.
 It features a mansard roof, characteristic of the Second Empire style.
 It was originally built to serve as a Presbyterian seminary for both sexes.
 It became a female academy and officially named Highland Hall in 1911.
 It continued to be used as a girls' school until 1940.
 It became a county office building in 1969.
Slifer House, also known as Administration Building-Evangelical Home, is a historic home located at Kelly Township, Union County, Pennsylvania.
 It was designed by noted Philadelphia architect Samuel Sloan and built in 1861, as a country home for Lewisburg merchant Eli Slifer (1818-1888).
 It has a 2 1/2-story, brick, square main section, with two rectangular rear wings.
 The main section has a hipped roof with cross gables in a Victorian style.
 It features wraparound and two-story porches and a four-story square tower.
 It has housed elder care facilities since 1916, when it was purchased by the Evangelical Association.

Question: Philadelphia-based architect Samuel Sloan created this building, also known as Nutt's Folly?
Answer: Longwood