Haller Nutt was one of the wealthiest cotton planters in the antebellum South, and in 1859 he commissioned Philadelphia architect Samuel Sloan to design something extraordinary. Sloan's plans called for an octagonal mansion of six levels, including a basement and rooftop observatory, crowned by a Byzantine onion-shaped dome visible for miles across the flat Mississippi landscape. The design was inspired by Sloan's own "Oriental Villa" concept from his 1852 book The Model Architect. Thirty-two rooms were planned, arranged around a central rotunda that would rise through the full height of the building to the Moorish cupola above. Nutt spared no expense, bringing skilled craftsmen from Philadelphia to execute the intricate woodwork and finishing. Built in part by enslaved people, the mansion was to be the grandest private residence in Natchez, a city already famous for its antebellum mansions lining the bluffs above the Mississippi.

When Confederate guns fired on Fort Sumter in April 1861, Longwood's Northern workers faced an impossible situation. They were skilled tradesmen from Philadelphia working deep in the slaveholding South at the outbreak of civil war. Most of them packed what they could carry and headed home, abandoning the project mid-stroke. The evidence of their sudden departure remains visible today: tools resting on unfinished surfaces, materials stacked for work that never resumed. Haller Nutt, watching his dream unravel along with the Southern economy, managed to complete nine rooms on the basement level with the help of local workers. The family moved into this finished ground floor and made it their home. But the war consumed Nutt's fortune along with the plantation system that had created it. He died of pneumonia in 1864, his great house still a skeleton above the first floor. His wife Julia and their children continued living in the basement rooms, surrounded by the ghost of what might have been.

Longwood occupies a peculiar place in architectural history. It was the final grand gesture of the cotton aristocracy, designed and begun at the very moment that world was about to collapse. The contrast between the completed and uncompleted portions of the house tells this story more powerfully than any textbook. Walk through the ground-floor rooms and you see the full flowering of antebellum taste: ornate plasterwork, fine woodwork, period furnishings arranged as the Nutt family once kept them. Climb to the upper floors and you enter a different reality entirely -- raw brick walls, rough timber framing, the skeletal anatomy of a building frozen mid-construction. Eight verandas were planned to ring the exterior at various levels. The onion dome, which gives Longwood its distinctive silhouette, was completed during the initial construction phase, so the building presents a finished face to the outside world while concealing its hollow interior.

Longwood survived decades of neglect and near-abandonment after the Nutt family could no longer maintain it. Today the mansion is owned and operated as a historic house museum by the Pilgrimage Garden Club, and it has become one of Natchez's most popular attractions. The unfinished state is purposefully maintained, not as a failure but as a powerful artifact of the Civil War's human cost. The house has also found a second life in popular culture: HBO used it for exterior shots of a vampire king's mansion in the series True Blood in 2010, and Bob Vila featured it in his Guide to Historic Homes of America for the A&E Network. From the air, Longwood's octagonal footprint and distinctive dome stand out unmistakably against the oak canopy of its grounds, a shape unlike any other building in the Deep South.