The man who officially opened Liverpool Metropolitan Cathedral celebrates his own milestone on Thursday.
Bishop Harris is marking 40 years as a bishop
The Rt Rev Augustine Harris, will be celebrating 40 years as a bishop in a special Mass at the cathedral.
It will be attended by Cardinal Cormac Murphy O'Connor, leader of the Roman Catholic Church in England and Wales and the Pope's Ambassador to Britain.
Liverpool-born Bishop Harris, 89, was the Bishop of Middlesbrough until his retirement in January 1993.
Bishop Harris, who was made an auxiliary bishop in Liverpool by Pope Paul VI in 1966, had to deputise for Archbishop George Beck - who was ill at the time - at the official opening and consecration of the cathedral in 1967.
Born in Tuebrook, Bishop Harris trained at St Joseph's seminary at Upholland near Wigan before his ordination in 1942.
In 1978 he was made Bishop of Middlesbrough by Pope John Paul II.
The bishop has kept busy in his retirement and is a frequent visitor to parishes for confirmation Masses in the Liverpool Archdiocese, which takes in Merseyside, South Lancashire, part of Greater Manchester and the Isle of Man.
"I never look at retiring as stopping work," he said. "You never stop being active if you don't want to be."
Among those attending will be the present Archbishop of Liverpool the Rt Rev Patrick Kelly and Catholic bishops from all over the UK.