Complex sentence: The Kilkenny Arts Festival also known as Kilkenny Arts Week was founded in 1974 by a collaboration of classical music enthusiasts though even then it was inclusive of many forms of art with Seamus Heaney giving a reading of his work.
Split into simpler sentences: The Kilkenny Arts Festival, also known as Kilkenny Arts Week, was founded in 1974 by a collaboration of classical music enthusiasts. Even then it was inclusive of many art-forms with Seamus Heaney giving a reading of his work.