Ferns Castle, an Anglo-Norman fortress, was built in the 13th century by William, Earl Marshall. Today about half of the castle still stands. The town also contains the 13th-century St Edan's Cathedral (Church of Ireland) this Cathedral is not the original one but the ruins of the original one can be found a few feet away from the existing one and the existing Cathedral today is not the fully restored Cathedral it was supposed to be (it was order by Queen Elizabeth I to be rebuilt to its former self by the O'Byrnes of Wicklow but they only restored part), which is the Cathedral today. It can be seen as an artefact and a museum and of course a church. The Tower and the Chapter House were added on in the 19th century. It also boasts several high crosses and parts of crosses.