Metropolitan borough

A metropolitan borough is a type of local government area in England. The term has been used in two different ways:

from 1900 onwards, there were 28 metropolitan boroughs (not counting the City of London, which had a special status) within the County of London. These were abolished in 1965 and replaced with London Boroughs within the much larger area of Greater London.
the current metropolitan boroughs are subdivisions of the six metropolitan counties, created in 1974. Originally these were lowe-tier authorities, but the metropolitan county councils were abolished in 1986, leaving the boroughs in charge of all local authority functions, and thus equivalent to unitary authorities.

List of metropolitan boroughs