The sleepy hamlet of Mittenwalde in eastern Germany could become one of the richest towns in the world if Berlin were to repay it an outstanding debt that dates back to 1562. A certificate of debt, found in a regional archive, attests that Mittenwalde lent Berlin 400 guilders on May 28 1562, to be repaid with six percent interest per year. According to Radio Berlin Brandenburg RBB.L, the debt would amount to 11,200 guilders today, which is roughly equivalent to 112 million euros. Adjusting for compound interest and inflation, the total debt now lies in the trillions, by RBB's estimates....