The cross is fixed to the outside of the Grade B-listed Gilfillan Memorial Church, in Dundee, which was built in 1887.
However, the Congregational church has not applied for planning permission to erect the cross.
Planning permission is required for any large signs or advertising billboards put up on the side of buildings.
The church will now have to retroactively apply for planning permission and provide details of how it has been secured to the building.
If not, it may be ordered to take down the cross – which it will also have to do if councillors reject its application.
The church, on Whitehall Crescent” has installed a large wooden cross on the Dock Street side of the Grade B-listed building, adjacent to the popular Malmaison Hotel.
The structure is at least 12 feet tall and hangs between the second and third floor of the church.
The church did apply for planning permission to replace its front door in March this year but the application was later withdrawn.
In 2015, if also sought planning permission to make repairs to the building”s south elevation, which overlooks Dock Street, but this did not include proposals for a giant cross hanging on the side of the property.
A Dundee City Council spokeswoman said the local authority is currently in discussion with the church about the cross.
She said: “We are continuing to engage in discussions with Gilfillan Memorial Church.”
Church minister Rev Dr Lee Rayner said: “It is an issue for the church”s management board.
“I know there were protracted discussions with the architects and Historic Scotland.”
Ken Dick from the church said he the joiner who installed the cross was responsible for securing planning permission.
Gilfillan Memorial Church was built in 1887 and listed in 1965.
Churches are exempt from listed building controls due to what is known as ecclesiastical exemption.
However, this is limited to the interior of the buildings.
Alterations to the exterior of a building must go through the secular planning system.
If the church”s application is unsuccessful and it is unable to reach an accommodation with the planning authority, the application will be referred to the decision-making body within the denomination concerned.