This is one of seven underground flour mills constructed by the British Military Services during the Cold War period (1950s) as part of the civil defence measures in order to keep the population provided with bread. These mills were constructed as a contingency measure against Malta being affected by potential nuclear attack within the Mediterranean region by the Soviet Bloc.

The complex which is entirely cut into the rock consists of an entrance passage circa three metres wide leading to the milling chambers where generators and machinery are placed at ground and upper floors. Adjoining the milling chambers are silos for the storage of grain and placed on the higher part of the site so that grain is fed into the mills by gravity and conveyor belts.

The mill is the one of two of the kind in working order and has been restored in recent times by volunteers and the local council. Other similar mills are extant around the Maltese islands, and some are already scheduled, such as the ones at Buskett and Xlendi. The latter is the only other mill in working order and which was also restored by volunteers. MEPA is also assisting the Munxar local council with the funding of the Xlendi mill's restoration through the Environmental Initiative in Partnership Projects.

Mepa scheduled the underground flour mill in Xemxija as a Grade 1 national monument as per Government Notice number 492/06 in the Government Gazette dated 6 June, 2006.