Greater Manchester Police estimates that 150,000 fans were in Manchester city centre for United's triumphant homecoming.
At least another quarter of a million people lined the streets along the rest of the route.
In Barcelona the previous evening Manchester United scored twice in injury time for a 2-1 victory against Bayern Munich to win the Champions League Final. In doing so they achieved the treble of Premiership, FA Cup and the Champions League.
Manchester United is the most successful soccer club in the world.
An RTÉ News report broadcast on 27 May 1999. The reporter is Brian O'Connell.