In Irish Mythos, a ''Fairy Fort'' was claimed to be defensive structures built by the enchanted Beings known as Fairies. From earthen mounds to stone and brick Circular structures, most were very ancient In reality, when ''discovered'' such Forts were actually ancient Neolithic structures, long forgotten. Without ''origin'', they would become the Fairy Forts of Irish Mythology. The earliest writings referencing them dates to the 7th Century AD.
