The area that was cordoned off in the centre of Monaghan Town yesterday has reopened following the discovery of a suspicious device.
Gardai arrived to the scene where the discovery of what is believed to be an old hand grenade was found.
The building site of the new Peace Campus near the North Road along Plantation Road was evacuated along with nearby buildings.
A cordon was established and the services of the Army Explosive Ordnance Disposal Unit attended the scene and carried out a controlled explosion last night.
In a statement to Northern Sound News, Gardai say the contents of the explosion were removed from the scene and investigations are ongoing.