The Glensheen Mansion is celebrating its anniversary by offering visitors free tours of the historic Lake Superior home.

The 39-room home, built by the influential Congdon family and completed in 1908, has an infamous history that includes the grisly 1977 murders of heiress Elisabeth Congdon and her night nurse.

Thursday's community day is celebrating the 36th anniversary of the home opening to the public as a museum, the museum's website notes.

The free standard house tours will be offered from 9 a.m.-4 p.m. on a first-come, first-serve basis. To get your free ticket, visit the ticket house in person at the base of the Glensheen parking lot.

Tickets are usually gone by early afternoon, the museum notes.

Community Day also kicks off the estate's return to its summer schedule, offering tours seven days a week.

Just a week ago, Glensheen Mansion opened the door to a room never before seen by the public. Robert's room, located on the third floor, can by viewed as part of the museum's expanded tour.

Robert was the youngest of the Congdon children.