An excavation in advance of new construction in Nieuwpoort, Belgium, has uncovered a cache of almost 500 medieval cannonballs. A large arsenal of medieval artillery assembled in a single location is an exceptionally rare find.The site behind the historic Stadshalle (city hall) is slated to become the towns new administrative center with the foundation stone to be laid at the end of the year. The Stadshalle has been there since the 13th century and test pits found evidence of archaeological material. Since February, archaeologists have been thoroughly excavating the grounds. They uncovered the remains of structures walls and floors from the Middle Ages, but the exact function and dates of the structures have not yet been determined.Given the age of the Stadshalle, medieval remains were expected finds, but archaeologists were astonished to discover dozens of cannonballs of varying size stored together less than three feet below street level. Stratigraphy dates the cannonballs to between approximately 1350 and 1600. These types of stone balls were fired from cannons, but also used as thrown projectiles in catapults and trebuchets. They are all carefully finished and rounded, however, which suggests they were intended to fit smoothly in the barrels of firearms.The balls were piled; they didnt land there randomly in battle. This was an artillery depot strategically located behind City Hall near the medieval southern city walls (now gone). One possible hint is a map from 1641 which depicts a cannon next to that wall close to the find site. The cannonballs may have therefore been an arsenal maintained by the city for defense.The archaeological fieldwork phase will be completed at the end of this week. This will be followed by an extensive research and reporting phase in which all finds will be further analyzed. Only then will it be possible to draw more detailed conclusions regarding the precise significance of the discovered structures and the cannonball depot.