Longest Continuous House Construction

Winchester House in San Jose, CA, USA, was under continuous construction for 38 years. Originally an 8-room farmhouse on a 161-acre estate, its transformation into a mansion was begun in 1886 by the widowed Sarah Winchester, heiress the Winchester rifle fortune. It is also called the Winchester Mystery House because of its many oddities, such as closets opening into blank walls, a window in the floor, and staircases leading nowhere. Some believe that after the death of her husband (son of the inventor of the famous Winchester rifle) the widow was convinced by a medium that endless remodelling would confuse and appease the ghosts of all the people killed by the "gun that won the west". The house has 13 bathrooms, 52 skylights, 47 fireplaces, 10,000 windows, 40 staircases, 2,000 doorways and  trapdoors and three elevators.