Cavendish won three Tour de France stages there, in 2008, 2011 and 2021.
"We placed road signs at 17 roundabouts at the entry points of the city as a nod and wink to him," Town Hall communications director Anne-Laure Bodin told AFP.
"We put up the signs at the start of July and they'll stay there until the end of the Tour de France," she said, explaining it was to mark the fast-man's legacy and connection with the town.
"He was happy by the looks of it because he made an Instagram post of it. It's fun but he deserves it."
Cavendish was a specialist on the flat stages and the finish line on Sunday's eighth stage is the same 3km home straight that suited the 'Manx Missile' so well.
"Now I'm truly humbled," Cavendish wrote on Instagram. "It's emotional to me as my first ever win.
"I hope it's a place as special for whoever wins there this year."
The 40-year-old Briton is now retired, and won 35 stages in total at the Tour de France, a record for stage wins he shares with all-time great Eddy Merckx.