The house in American Horror Story is purely fictional. It's a part of the creative imagination of the show's writers and producers. They designed it to add to the horror and mystery elements of the story.
To be honest, I don't have the exact details on the specific house it's based on. But it could draw elements from multiple haunted house concepts in popular culture.
One of the scariest things is the psychological horror it presents. The characters often face extreme situations that mess with their minds. For instance, the way they are haunted not just physically but also mentally by the events in the house. The show also uses sound effects really well to enhance the scariest moments, like creaking floors and strange whispers in the dark.
Ben Harmon is also a main character. He is Vivien's husband and they both face numerous horrors together in the house. He is a psychiatrist which adds an interesting layer as he tries to rationalize the supernatural events with his knowledge. There are also other characters like Constance Langdon who is a rather complex and spooky neighbor. She has her own secrets and connections to the house.
The murder house in 'American Horror Story' is located at 1120 Westchester Place. This address is significant as it is the site of numerous gruesome murders and paranormal activities throughout the season. All kinds of dark secrets are hidden within the walls of this house at that address, which makes it a central and spooky element in the story.