Tens of thousands of people are flooding into the small Co Meath village of Slane for the 21st in series of (almost) annual rock concerts.
Today’s gig, headlined by Welsh posters Stereophonics, with support from The Charlatans, Nickelback, Counting Crows, Ocean Colour Scene, Doves and Irish band The Revs, is set to attract over 50,000 fans.
Last year over 200,000 people attended two concerts by U2 at the natural amphitheatre at Slane Castle.
Gardaí have mounted a huge security operation around the town, closing it off and blocking traffic from entering the vicinity.
Around 600 gardaí will be on duty and the local district court will hold a special sitting to process arrests.
They are also warning concert-goers of the dangers of trying to cross the River Boyne to gain entrance to the gig. A number of people have drowned in previous years.
Met Éireann has forecast largely fine weather for the rest of today.