Estonia has two Unesco World Heritage sites. The historic old town of Tallinn is well known for its wonderfully preserved medieval architecture; more obscure is the Struve Geodetic Arc, which Estonia shares with Belarus, Finland, Latvia, Lithuania, Norway, Moldova, Russia, Sweden and Ukraine. It is a chain of survey triangulations stretching from Hammerfest in Norway to the Black Sea, which yielded the first accurate measurement of a meridian (now you know).