Official Government Website

Dennis the Cat Day

Enjoy a summer Sunday at the Old Idaho Penitentiary in celebration of Dennis the Cat, the Old Idaho Penitentiary’s historic animal mascot. Join staff for Prison Pets presentations (free with your pet food donations for Simply Cats and the Idaho Humane Society), limited edition Dennis merchandise, food trucks, local vendors, and more!

Sunday, May 28 (12:00 pm – 5:00 pm, last admission 4:00 pm).

Registration is $10 per person and FREE for Idaho State Historical Society Members! Become a Member at

Between 1952 and 1968, Dennis lived among the staff and residents of the Idaho State Penitentiary, becoming one of the site’s best liked and most respected figures. Upon Dennis’ death in 1968, the prison population buried him nearby within the main yard, fashioning a durable engraved headstone marking his resting place during his funeral services. Today, guests of the Old Idaho Penitentiary regularly pay their respects at his stone, the only marked grave within the prison walls.



May 28 2023


12:00 pm - 5:00 pm

More Info

Register Now


Old Idaho Penitentiary
2445 Old Penitentiary Rd., Boise, ID, 83712

Leave a Reply

ver: 3.5.2 | last updated: