I got to visit Longwood in Natchez, MS, a massive octagonal mansion on which the construction was halted with the outbreak of the Civil War. With only the lower level finished, the upper floors remain in the same state they were in over 150 years ago. Apparently the deal between the current and past owners required that it remain unfinished, giving visitors a rare glimpse into the past. The workmen's tools are still laying around. A few of the shipping crates, including a massive one for the house's piano, serve as the only furnishings on the first level. In it's unfinished state, you can stand in the center of the house and make yourself dizzy looking straight up through the next six stories worth or lumber and rafters. I can't think of a better setting for a ghost story; something where you can hear workers' saws and civil war gunfire after the sun goes down. I'd stay there overnight... I swear.