On 25 May 1967, Scottish football reached a pinnacle of success unsurpassed in the modern era when Celtic defeated Inter Milan 2-1 in Lisbon to lift the European Cup.
Celtic were the first British team to win the European Cup
Less than 24 hours earlier, Kilmarnock had exited the semi-finals of the Fairs Cup at the hands of Leeds United.
And, just six days after Celtic's triumph, Rangers failed to overcome Bayern Munich in the final of the European Cup Winner's Cup in Nuremberg.
Forty years on, Scottish clubs can only dream of making such an impact in Europe and Celtic are celebrating the finest moment in their illustrious history.
Jock Stein's side wrestled the greatest prize in club football from the preserve of Europe's Latin sides for the first time since the tournament's inception in 1956.
A crowd of more than 45,000 crammed into the Portuguese national stadium, most of them travelling Celtic fans, to witness the Glasgow team upset the odds.
Before kick-off, few believed Celtic were capable of overcoming the negative defensive tactics of Helenio Hererra's outfit, who had dismissed CSKA Sofia, Real Madrid and Torpedo Moscow en route to the final.
The 11 players were all born within 30 miles of Celtic Park
But Stein's side had a strong self-belief and their football was both exciting and attack-based, pioneering the concept of 'total football' years in advance of the Dutch masters.
According to the Celtic players, Stein's instructions ahead of the game were simple: go out and enjoy yourself.
The plan almost came off the rails in the opening moments when Jim Craig felled Renato Cappellini in the box, for Sandro Mazzola to net the resulting penalty with barely eight minutes on the clock.
Celtic responded by laying siege to the Italian goalmouth, and Inter reverted to their famous defensive pattern and goalkeeper Giuliano Sarti made some marvellous saves.
When half-time arrived, the score remained 1-0, but Stein knew that Celtic were capable of scoring from any position on the pitch, and shortly after the break the equaliser arrived - from the boot of left-back, Tommy Gemmell.
In the 65th minute, the big defender linked up with Craig and Bobby Murdoch to send home an unstoppable shot.
The Italians had no answer to Celtic's enterprising play and were finally undone seven minutes from time.
Murdoch led another blistering attack and sent in a powerful shot on goal from distance, which Stevie Chalmers deflected into the net.
Billy McNeill was the first British player to lift the European Cup
When German referee Kurt Techenscher sounded the whistle for full-time, the Celtic players were engulfed in a pitch invasion, with euphoric fans spilling onto the pitch to congratulate their heroes.
Club captain Billy McNeill had to be ushered around the outside of the stadium under armed escort, and then climbed the stairs to the presentation podium, where he was handed the massive, gleaming trophy.
Celtic, at their first attempt, became the first British side to win the tournament - and did so with a team comprised entirely of home-grown, local players.
The 11 players who walked out on to the Estadio Nacionale pitch on that sunny afternoon in May were dubbed 'The Lisbon Lions', and their story is legend.
At the final whistle, Stein said: "There is not a prouder man on God's Earth than me at this moment.
"Winning was important, aye, but it was the way that we won that has filled me with satisfaction.
"We did it by playing football; pure, beautiful, inventive football."
Celtic: Ronnie Simpson, Jim Craig, Tommy Gemmell, Billy McNeill, Bobby Murdoch, John Clark, Steve Chalmers, Willie Wallace, Jimmy Johnstone, Bobby Lennox, Bertie Auld.
Goals: Gemmell (63), Chalmers (83).
Inter Milan: Giuliano Sarti, Giacinto Fachetti, Aristide Guameri, Tarcisio Burgnich, Armando Picchi, Gianfranco Bedin, Sandro Mazzola, Mario Corso, Angelo Domenghini, Mauro Bicicli, Renato Cappellini.
Goal: Mazzola (pen 8).
Referee: Kurt Techenscher (West Germany)
Jock Stein: You're Immortal. BBC ONE Scotland, Friday May 25, 23:05.