The team lost one of its stars today.
Celtic has lost one of its heroic figures, following the death of Lisbon Lion Tommy Gemmell.
Gemmell was part of a Celtic side that achieved an historic feat in May 1967, by becoming the first British team to capture the European Cup.
Following his passing after a long illness, we look back at that Lisbon Lions team and their journey to European glory.
At the outset of the season, Celtic had no designs on chasing a European trophy. With a squad that came predominantly from the surrounding local Glasgow area, it wasn't apparent that they had the pedigree of players needed to thrive on the European stage.
Meanwhile, Manager Jock Stein, who had previously visited Italy to study the methods of Inter Milan boss Helenio Herrera, was privately masterminding a triumph.
They travelled to Lisbon to take on an Inter Milan side that played a defensive brand of football.
Prior to that season, no British side had even qualified for the final of the European Cup until Celtic emerged as unlikely contenders.
Scottish football legend Pat Nevin, who was just a boy at the time, aptly describes the atmosphere that preceded the decider.
"There was a goodie vs baddie thing going on. The Italians were the favourites, they were very defensive, very organised, very professional. And these mad Scotsmen came in and upset the apple cart."
The draw of Celtic's bid for the European Cup, compelled fans to go to extraordinary lengths to get themselves to the Portuguese capital.
One fan willingly sacrificed his marriage to afford the trip.
Ernie Wilson told the FourFourTwo that he proposed selling his house, moved in with his mother and invested the deposit in following Celtic to Lisbon. His wife, unimpressed by this, ended the marriage when he returned.
"It was worth every penny though," he recalls.
Moments before taking to the pitch to face Inter Milan, the Celtic team assembled in the tunnel beside their Italian opponents.
And to prove they weren't intimidated by the challenge that lay ahead, midfielder Bertie Auld led the players off in a rendition of 'The Celtic Song.'
The Scottish side suffered the worst possible start after Inter Milan were awarded a penalty which was converted by Sandro Mazzola.
But rather than provoke despair among the Celtic players, the setback galvanised them and they rallied back.
Billy McNeill, who captained that Lisbon Lions team said:
"It meant that there was only one way that we could go then. We'd to forget everything other than get ourselves back into the game. We actually raised the tempo to such an extent that the Italians were really surprised."
They generated several goal chances and their persistence resulted in Tommy Gemmell scoring the equaliser with a thundering shot from outside the box.
With momentum on their side, Celtic snatched the decisive goal five minutes from the end. Bobby Murdoch threaded a shot into the penalty area which was deflected into the net off the boot of Steve Chalmers.
Euphoria ensued at the final whistle as Celtic fans spilled out onto the pitch. A number of players then had to try and clamber over the fans and retrieve false teeth they kept in Ronnie Simpson's cap at the Celtic goal.