Without doubt Dublin's finest attraction is Kilmainham Gaol. This grand Victorian prison has a fascinating story that's brought to life by a polished tour.
As with much of Dublin's historical attractions, the focus of the tour is on the leaders of Irish revolutionary struggle, especially those from the 1916 Easter Rising who were incarcerated and executed here a century ago.
The evocative guided tour - real human beings, no audio guide malarkey - takes you from the chapel that was famously the location of the pre-execution wedding of a 1916 leader, through the cells of many notables and out to the execution yards. There's also decent exhibition to end with which explores the Victorian prison system.
We moan a lot about crowds and queues on these pages - I think there is a 400-word rant somewhere about the last time I went to buy milk - but whilst being one of Dublin's most visited attractions, Kilmainham Gaol does not suffer this curse. This is thanks to the fact that you can only book onto slots for the guided tours with no free roaming allowed. With a maximum of 15-20 people around you at any one time, you will see what you came to see and your photos will not be impeded by the backs of the heads of a a sea of people.
This being said, it is absolutely essential that you book online at least a few days in advance in order get a space at this perennially busy attraction. Being in the west of the city centre, you can't just pop in to check. Once you've got an expensive taxi, jumped off the sightseeing bus or walked a heck of a long way then you're kind of stranded. Also, the Dublin buses aren't the easiest to use to navigate so plan well in order not to miss your spot. It is well worth this relative hassle though.