Bomb disposal experts were called to Bassetlaw museum after staff discovered explosives in the attic today (Thursday 20th March).
The Retford museum was evacuated and temporarily closed after the curator uncovered three old hand grenades and a handful of bullets.
It is understood they were looking for items to display in an upcoming D-Day exhibition.
Ministry of Defence bomb disposal experts swooped on the Grove Street museum along with Notts Police at around 1.15pm.
But the all clear was given after the munitions were found to be inactive.
The museum opened again later this afternoon and will be open as usual tomorrow (Friday).