These huge concrete rings were built by the Germans during World War II on the coast of the Barents Sea. For decades, the Soviet military limited access to them after the war was over, fueling ...

n October last year, Steve and Olaf travelled to Muirkirk in Maryland, where they photographed a similar concrete ring and ...

Add Yahoo as a preferred source to see more of our stories on Google. A modular, precast system of concrete 'rings' can be connected in different ways to build a range of models of energy-efficient ...