Dublin Castle was founded in 1204 on the orders of King John of England, built to protect the crown's jewels. It did not do a perfect job.

In 1907, the Irish Crown Jewels vanished from a safe inside the walls. Suspicion fell on Sir Arthur Vicars, the officer of arms, and his friend Charles Shackleton, brother of explorer Ernest. Shackleton had ties to prominent gay men in Dublin and London and was never questioned. The jewels remain missing.

For seven centuries, the castle was the seat of British rule. When Collins arrived for the handover in 1922, the outgoing Lord Lieutenant complained he was seven minutes late. Collins replied that they had been waiting seven hundred years, so he could have his seven minutes.

VoiceMap's self-guided audio tours trace the castle's arc from Red Hugh O'Donnell's escape through a drain in 1592 to the Easter Rising's first casualty at its gates.