The Irishman boarded a plane to Portugal along with a group of the Lisbon Lions who became the first footballers in Britain to lift the European Cup almost five decades ago.
Their 2-1 triumph over Inter Milan in Lisbon in 1967 is being honoured by the Glasgow club which took the veterans back to Lisbon for tomorrow's UEFA Champions League Final between city rivals Real Madrid and Atletico Madrid.
Celtic ambassador and Lisbon Lions captain Billy McNeill said: "This is a magnificent gesture by the club and one which is greatly appreciated by all the boys and the families of everyone connected to the team."
Lennon will help Celtic choose his successor after announcing he is moving on to a "new challenge".
The Northern Irishman said: "Serving the club was always a privilege. I have always given my best and aimed to do all I can to ensure success for Celtic. I will now assist the club in appointing my successor."