The Garda Museum tells the story of the Garda Síochána, Ireland's national police force, from its foundation at independence in 1922 to the present day. The small collection covers uniforms, weapons, documents, and photographs tracing the force's development through some turbulent periods of Irish history.
Entry is free and the museum is located within the Dublin Castle complex, making it an easy addition to a visit to the castle or the Chester Beatty Library. It's a niche interest but well presented, and provides some context for understanding 20th-century Irish history.