At the World Assembly of Cities and Local Authorities (WACLA) in Istanbul-1996, participants called upon the international local government organisations to strengthen their coordination and create the basis for a unified world organisation.

United Cities and Local Governments is the result of the unification of the two largest generalist international local government associations, the International Union of Local Authorities (IULA) and the United Towns Organisation (UTO/FMCU).

Metropolis, as the leading world organisation representing major metropolises, has reached an agreement with the new organisation to undertake the management of its Metropolitan Section and to be represented at their governing bodies. Active members of Metropolis may become members of the new metropolitan section and the new organisation through a joint membership fee.