Gumbo was visiting the Kilmainham Gaol (jail) in Dublin, a popular destination as you can tell from the line of people waiting to get in the front door. Congratulations to the following people who solved this puzzle! In order of notifying us (by email), these were: PortMoresby, TravelingCanuck, and Roderick Simpson.
Kilmainham is one of the largest unoccupied prisons in Europe. As you can see from the above photo, the prison's entrance had some usual and interesting artwork.
Kilmainham is situated on the west part of Dublin, not far from the famed Guinness Storehouse (where according to his answer, we'll also find Roderick Simpson!) There's a lot of Irish and English history here, including of Irish suppression and rebellion, so it makes for an interesting stop especially if you're in the city for several days.
The jail opened in 1796, as the Dublin County Jail and as a debtor's prison. At that time it was considered a model prison, but by modern standards it was a stark and cold place to be confined. It was often used by the British as a political prison, especially to incarcerate those who fought for Irish independence, including those of the firing squad execution of political leaders of the 1916 Easter Rebellion. The jail was closed in 1924.
The museum offers a one hour guided tour, well worth doing, which includes a 15 minute history presentation in the prison chapel. It's quite an experience to tour the cells in the cavernous east wing of the prison....
You continue through several courtyards, between these stone buildings.....
including the courtyard where we saw the impressive metal spikes of our initial puzzle photo......
And ending in the Stonebreaker's yard, the site of the 1916 executions.
When we visited there was a large collection called "Roses from the Heart" on display in the East Wing. This is a carpet-like display of bonnets hand-made to commerative the suffering of women and children who were help in prison here, many of whom were sent to Australia.
(Roses from the Heart exhibit)
The tour ends at a small museum which features life in a Victorian prison and displays on Ireland's fight for independence.
If you would like to learn more about the Gaol and it's layout, please download the pdf of the brochure at this link.
Of note, a large part of the prison is undergoing renovation currently, to be completed about the end of 2015.