BOMB squads were called after a hand grenade was found on a roof in the middle of Solihull town centre last Saturday.
A full-scale emergency was triggered after the explosive device was discovered on top of The Priory, in Church Hill Road, at around 11.15am.
Police set up a 100 metre cordon around the building - which is the home of Solihull's Age UK and the Citizens Advice Bureaux.
Its understood the grenade was found while work was being carried out on the roof and police are now investigating how it got there.
Officers have not confirmed if the device dates from the Second World War or was manufactured more recently.
Following the find, just yards from the Touchwood shopping centre and Solihull High Street, police advised motorists to avoid the area.
Traffic was diverted in the vicinity of Homer Road, New Road and Church Hill Road itself, while the grenade was made safe by the experts.
Touchwood was allowed to remain open while the incident took place and the cordon was removed at around 2pm.
A Touchwood worker first heard about the grenade when she was walking into the centre of Solihull to start her shift.
The 18-year-old, from Solihull, who didn;t want to be named, said: "A police car had blocked the road, they said there was a hand grenade there.
"They had shut off this part of Solihull for public safety."
Shopper Stuart Millington, aged 34, who works at Land Rover and lives in Solihull, said he was stunned by the drama.
I'm really surprised, it's a bit of a random place to find something. It just makes you think what would've happened if it had gone off."