Cordons were put in place around Northampton's Cultural Quarter after workers discovered what was thought to be a bomb.
Guildhall Road, Derngate, St John's and Angel Street were taped off following reports of the suspected device this morning.
It is believed workers at the Vulcan Works development discovered a suspicious object during the renovation in Angel Street this morning (Thursday, June 6).
Police were called at 10.15am and were in attendance there throughout the morning.
However, the cordon has now been lifted and the suspicious object has been confirmed as benign.
A Northamptonshire Police spokeswoman said the item was found to be an "as-yet unidentified, but non-explosive object".
However, a Northampton Borough Council spokesman has cleared up the mystery.
“During CCTV investigation of the site’s drainage system, an unusual object was discovered," he said.
“A precautionary cordon was put in place and contractors worked with police to capture detailed images which were then sent to the MOD’s Explosive Ordinance Disposal which confirmed it was a large mallet.”