Essential work to repair damaged areas of Newport Arch in Lincoln began on Tuesday, October 15, after a brief delay.
They will also add an extra layer of stones to create a protective barrier on the stones exposed at the top.
As well as to combat general corrosion, the work is needed due to winter frost and wet winters causing damage.
Work was meant to begin on September 23, but due the stonemason being busy with restoration efforts at Lincoln Castle, work had to be pushed back.
The City of Lincoln Council are able to do the work thanks to a £60,000 Heritage Fund grant from WREN.
The work will take eight weeks to complete, but the arch will remain open to traffic in this period.
Newport Arch is one of the only Roman arches left in the country allowing vehicles to pass though.
However, a lorry crashed into it in 1964, causing extensive damage and placing the arch on English Heritage’s “at risk” register.
Michelle Smith, Regeneration Officer at the City Council, said: “The repair works to Newport Arch will only be taking place during normal working hours.
“However, the scaffolding works were carried out overnight as not to disrupt traffic flow through the arch.
“We will be having regular meetings with the contractors throughout this project to ensure those living around the arch have as little impact as possible from the works.”