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Dennis the Cat Day

Join the Old Idaho Penitentiary on a Summer Sunday afternoon and discover the story of the Penitentiary’s historic animal mascot, Dennis the Cat during our fourth annual Dennis the Cat Day!
Activities include Prison Pets history presentations, Prison Paws scavenger hunt and more! Food trucks, beer and alcohol, local pet supply vendors, special presentations, new Dennis merchandise, and more will be available!

Dennis the Cat Day: Sunday, May 26, 12:00 pm – 5:00 pm (last admission 4:00 pm). All ages welcome.

Be sure to bring donations of unopened pet food for admission to the Prison Pets history presentations. Donations benefit the Idaho Humane Society and Simply Cats, Boise’s cageless, no-kill, feline adoption center. Presentations take place at 12:30, 1:30, 2:30, 3:30 and 4:30pm.

Idaho State Historical Society Members receive free admission to this event! Become a Member at Members must bring pet food donations for presentations.

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 26 2024


12:00 pm - 5:00 pm



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