In my opinion, Grand Opera House in Oshkosh, JFK Prep in St. Nazianz Ed Gein former homestead site in Plainfield. Clarks True Value in Plainfield. (The site of Gein's only convicted murder), and various sites I would rather not list. E-mail me for more info.
Here's my list of 15 haunted places in Wisconsin, listed in alphabetical order:
Amery - Amery Lutheran Church Appleton - Appleton Curling Club Balsam Lake - Johnnie B. Dalton's Christie - Charlotte Mills Bridge Eau Claire - Fire Station No. 10 Elk Creek - Elk Lake Dam Fond du Lac - Hotel Retlaw Genoa - Whiskers Olde Tyme Inn Janesville - Spaulding House Antiques Kenosha - Rhode Opera House Kewaunee - Historic Karsten Inn Menomonie - Mabel Tainter Theatre Mineral Point - The Walker House Washington Island - Nelsen's Hall Wisconsin Dells - Captain Brady's Showboat Saloon
They make my list because they have each had multiple eyewitness encounters with the paranormal. I have visited all of these locations and in most cases had the opportunity to speak with some of the people who related their firsthand experiences.