- This event has passed.
Dennis the Cat Day
May 28 @ 12:00 pm – 5:00 pm MDT
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!