02Fort Camden

TrevOC / Getty Images

Originally built in the 16th century, Fort Camden was then restored in the 1860s and is now a piece of living history. As well as exploring the historic walls, there are also some permanent exhibitions you can take a look at. These include a presentation on a Brennan torpedo, which was the world's first guided weapon, as well as a resident 9/11 exhibition. Fort Camden, or Camden Fort Meagher as it's known in Irish looks over the entrance to Cork Harbor. This is one of the world's largest natural harbors and has had protective forts present there since 1550. Many of the original features of the fort have been restored, such as the spiral granite staircase, and the Bright Tunnel - a 160 feet tunnel that runs from the top of the fort to the bottom.