It won't be open for the next fortnight.
Matlock bridge, which carries the A6 over the River Derwent, will close for two weeks from Monday 16 September to allow for vital work by Derbyshire County Council and the Environment Agency to take place.
The bridge will need to be closed to both pedestrians and vehicles as a large crane, which will take up the whole width of the bridge, will be used to carry out the work.
The work is to protect the bridge and reduce the risk of flooding.
Derbyshire County Council will fill in holes in the river bed and gaps around bridge supports, caused by erosion. The Environment Agency (EA) will also be removing a build up of silt.
Once the work is complete it means water will drain away more efficiently if the river were to flood.
Councillor Simon Spencer, Derbyshire County Council’s Cabinet Member for Highways, Transport and Infrastructure, said: “This is essential work to protect the bridge and reduce the potential for flooding. We will carry out the work as quickly as water levels and the weather allow and re-open the bridge as soon as possible.
“We apologise for any inconvenience caused and thank everyone for their patience while we make these improvements to flood protection in the town.”
During the bridge closure signposted diversions will be in place. For motorists the alternative route is along Derwent Way, Bakewell Road, Crown Square and vice versa.
Pedestrians will need to use Dale Road, cross over the footbridge into Hall Leys Park, walk through the park to the town centre and vice versa. If the bridge can safely be opened to pedestrians outside of working hours it will be.
Nick Le Mare, from the Environment Agency, said: “This work, in partnership with Derbyshire County Council, will not only improve flood resilience, but also help prevent further erosion at Matlock Derwent Bridge.”