“Here, put these gloves on first. We must have some rules.” With that, ordnance expert Peter Ewler grins, then allows me to dip my hands into a bin of high explosives and lift out a 50-pound unexploded bomb.

The rusted thing, from World War II, is of Russian origin and was found near the Polish-German border. If my hand slips, the concrete storage bunker we’re in probably would blow up.

Unexploded bombs are still big business in Germany. Almost two million tons were dropped there by the U.S., Russia and Britain during World War II. An estimated 10 percent to 15 percent never exploded and now, seven decades later, are prolonging war into the 21st century.

In Brandenburg alone, the area surrounding Berlin that I visited and the most infested of Germany’s states, around 350 tons of unexploded munitions are destroyed annually, including grenades, mortars, artillery shells, mines and aerial bombs. Some are found in fields, others in residential areas near homes and schools built after the war....