The H.H. Holmes' Murder Castle in Chicago was named the most haunted house in Illinois, according to a new report.
Big 7 Travel created a list of houses in each of the 50 states, ranking a Chicago home as the "most haunted" in Illinois.
Holmes built the castle in Chicago's Englewood neighborhood, where he contracted various different people to carry out the building process, according to the website.
Holmes reportedly did not want anyone to know the real floor plan, which is why no singular person built the home, Big 7 Travel said.
The website said workers at the current building "often note how uneasy they feel when they visit the basement."
Holmes was one of America's first noted serial killers, according to a report from Concordia University in St. Paul, and known for killing at least 27 women during the 1893 World's Fair in Chicago.
Big 7 Travel said some historians believe Holmes could have killed at least 200 victims.
The report said Holmes would lure victims into the murder castle, which was designed as a two-story maze with trap doors, hidden passages and torture chambers.
The castle was completed in 1892, one year prior to the opening of the World's Fair, according to the report.
An Elgin haunted house based its story line off Holmes' story, also used in Erik Larson's "The Devil in the White City."
The owner of Terror in the Timbers explained that women used to come to the World's Fair from Illinois and surrounding states, where a man would prey on those unfamiliar to Chicago. He said the haunted house's story shows his victims can be found in Elgin.