Fire Wednesday morning at the Marathon County Historical Society museum in Wausau caused "significant" damage. Battalion Chief Tom Leslie says firefighters were able to spread tarps over the histroric artifacts at museum as they battled the blaze, which began on the third floor. The building is undergoing a $3-million renovation. Leslie says heat guns that contractors were using to remove paint likely caused the fire. The museum was built in 1901 as a mansion by lumber barons Cyrus and Alice Yawkey.