Manic Street Preachers, David Gray and Cathy Davey are among the headline acts taking to the stage in Ireland for Arthur's Day later.
Guinness has recruited hundreds of artists and acts to mark the day around the world.
Following last year's celebration of 250 years since Arthur Guinness signed the 9,000-year lease at St James' Gate, Guinness is keeping the party going.
Celebrations will begin at 17.49 (5.49pm) at the Dublin city centre brewery and continue with events taking place all around the world.
In Ireland, Paolo Nutini and Oscar-winning actor turned musician Tim Robbins will also be among 60 acts taking to the stage.
Hundreds of other acts are meanwhile lined up to play in pubs in Galway, Cork and Dublin for the evening.