A handgun was found in the Glenfada Park area of the Bogside on Tuesday afternoon.
It is believed the weapon was discovered by workmen carrying out renovation work in a flat in the area and had been concealed behind a fireplace.
The gun is believed to have been concealed in the wall for some time and was quite old.
The PSNI were called to the scene shortly after the discovery was made and removed the gun.
The area was a scene of frequent gun battles during the height of the Troubles in the city in the 1970s and 1980s.