Is Winchester Mystery House haunted?
United States Reported haunting level 4 of 5

What actually happened
The 1906 earthquake damaged the mansion so badly that the seven-storey tower and most of the fourth floor were later demolished.
The history
Sarah Winchester, widow of the rifle heir, bought a farmhouse here in 1886 and kept builders at work for 36 years until her death on 5 September 1922. The house opened to the public on 30 June 1923.
What people report
Visitors have reported footsteps and door latches turning in the empty wings, and tradition holds that the endless building was meant to confuse spirits.
That paragraph is reported tradition, not a claim about what is there. The history above it is sourced; the stories are recorded because people tell them.
Visiting
525 S Winchester Blvd, San Jose, CA 95128, United States