Manchester City Council has told landlords to remove unauthorised extensions from dozens of houses on just three streets following complaints from residents.
The City Council has issued enforcement notices to the owners of 24 houses on Braemar Road, Brailsford Road and Moseley Road in the Fallowfield area.
The notices - 14 of which have been served on just two landlords - relate to poorly designed first floor rear extensions which have been put up without planning permission, which would have allowed the landlords to come back with more appropriate and acceptable designs.
Once the notices have been served, the owners have up to nine months in which to remove them and restore the properties to their original condition. If they fail to do this, they could be taken to court where magistrates could issue fines of nearly half a million pounds - or up to £20,000 per property.
The owners are now able to appeal to the Secretary of State for Communities and Local Government.
Councillor Nigel Murphy, Manchester City Council's executive member for the environment, said: "It's very unusual to have so many unauthorised extensions in such a concentrated area, and this has had a real impact on the appearance of the neighbourhood.
"We encourage investment in properties which improve the look of our neighbourhoods and we ask developers and homeowners to first contact our planning department to discuss any proposed alterations. However, we will always follow this action when developers build extensions that are poorly designed and have a negative impact on a neighbourhood."