The certificate was uncovered by Mittenwalde’s town historian, Vera Schmidt. As the debt came with an annual 6 percent interest rate Berlin would owe Mittenwalde 11,200 guilders today — equivalent to about €112 million ($137 million).
Once the number is adjusted for inflation and compound interest, the figure comes out somewhere in the trillions.
Berlin — a city already €63 million ($77 million) in debt — may have some hope, however. The promissory note is missing the seal, which may render it invalid, the Financial Times of Deutschland reports, though historians are quick to point out that seals weren’t widely used until the 17th century. Berlin has repaid part of the debt, at least. A ceremonial guilder, dated back to 1539, was given to Mittenwalde by Berlin’s finance minister, Ulrich Nussbaum. If it ever reached the market, the 3.25 ounce, 18 karat gold piece would go for somewhere in the range of €50,000 to €100,000. ($61,000 to $122,000), reports the Berliner Zeitung.
Apparently this isn’t the first time the certificate has been found, nor the request for payment been made though. Mittenwalde has been asking Berlin for payment every 50 years or so since 1820, according to the Berliner Zeitung.