The 13th-century Record Tower is the only intact tower from the mediaeval period of Dublin Castle, and was used as a high security prison. The battlements were added in the early 19th century, around the time the adjoining gothic revival Chapel Royal was built.

It was from this tower that Red Hugh O’Donnell, Art O’Neill and Henry O’Neill made their escape on a winter’s night in 1592, setting out for Glenmalure after lowering themselves down the toilet chute. Participants in the Art O’Neill Challenge usually skip that part.

Just outside the walls of Dublin Castle, the Dubhlinn Garden occupies the site of the ‘black pool’ on the River Poddle that gave Dublin its name in Viking times. The Irish name of the city, Baile Átha Cliath, comes from the older Gaelic settlement at the ‘ford of hurdles’ that crossed the Liffey nearby.

The colours of the walls are reminiscent of the logo for the Dublin Millennium in 1988, the year of Anna Livia, milkbottles and fifty-pence pieces.