Three hundred photos were collated for the occasion, to which every former city councillor and mayor that could be contacted has been invited.
Mr Crosby said he wanted it to be about all the people that had participated and supported him in a journey which culminated in 12 years as mayor. "I did not want it to be all about me."
Also at the get-together were some of the council chief executives and key managers with whom he worked closely as a committee chairman and then as mayor.
Mr Crosby's local government career began with his election on to the former Tauranga Borough Council's Papamoa Community Council in 1986 - the equivalent of today's Western Bay of Plenty District Council community boards.
The big shake-up of local government in 1989 saw Tauranga City Council amalgamate with the Mount Maunganui Borough Council, with Papamoa and Bethlehem also brought into the city.
Mr Crosby said the restructuring, which significantly reduced the number of local authorities in New Zealand, was controversial. "Some Mounties are still talking about it."
The best time to achieve one council covering all the Western Bay would have been in 1989, but the rural sector wanted its own council, he said.
The promise Mr Crosby showed as a young city councillor was recognised by Mayor Keith "Nobby" Clarke when he was made chairman of the regulatory committee in his second 1992-95 term on the city council.
"It was a good committee to cut your teeth on because you did a lot of the city planning issues."
It set him up to take over as chairman of the powerful policy and strategy committee and, under Mayor Noel Pope, he planted his foot firmly on the ladder by his appointment as deputy mayor.
Mr Crosby said the knowledge he had gathered would be put to good effect if he was elected as one of the Tauranga representatives on the Bay of Plenty Regional Council.
A lot of the key initiatives that impacted on the city council now went through the regional council first, with proposed new legislation giving the regional a far stronger role in growth management. Mr Crosby was also attracted by the regional council's environmental focus.
The MC for the function was Hits radio host Will Johnston who led the discussion on the major issues during Mr Crosby's 30-year local government career.
Mr Crosby's valedictory and parting speeches will take place at the final meeting of the city council on September 29 before a new council was elected on October 8.