STOCKHOLM, SWEDEN—According to a report in The Local, hundreds of seventeenth-century cannonballs in various sizes have been found in central Stockholm, in an area where iron was once produced in large quantities for export. Grenades, hand grenades, and parts of cannons were also uncovered. Archaeologists led by Michel Carlsson think the cannonballs may have been dumped when the city grew and its fortifications were moved in the early seventeenth century, or when the city’s iron-weighing facilities were moved in the 1660s. “One question we are considering and have not yet found the answer to is why the cannonballs were not saved—if nothing else than for the sake of the metal value,” Carlsson said. To read about a sixteenth-century Swedish warship that sank in the Baltic Sea, go to “Mars Explored.”