Archimedes would be proud of the town of . So would Sam Eyde. Rjukan, home to about 3,500 residents and situated about 70 miles west of the capital, Oslo, has installed a trio of giant mountaintop mirrors to focus light into the valley town’s square during the cold (and dark) winter months. Legend has it that on the advice of mathematician and inventor Archimedes, the town of Syracuse during the Siege of Syracuse. A hundred years ago, Eyde, a founder of Rjukan, first proposed adapting the idea to warm up the chilly town. The three 550-square-foot mirrors, built at a cost of $825,000, couldn’t stay focused for long without sensors and computer control to follow the sunlight and keep it aimed at the center of town. So, in Eyde’s time the project wasn’t practical. Instead, in 1928, the town built a cable car leading to the top of a mountain so residents could take a short ride to the warming sunlight.