An Irish Harp Festival was a celebration of Irish music and harps on Earth.
In 2264, the festival was held in Mandela City in the United States of Africa. Lieutenant Nyota Uhura visited the festival while the USS Enterprise was undergoing repairs. She purchased an Irish harp at the festival and brought it back to the Enterprise with her, much to the fascination of Commander Spock. (TOS novel: Enterprise: The First Adventure).