The fragment of the Poland map with Ryn town in the centre. The town is located between Ryn and Ołów Lakes and accommodates Ryn Castle, the second biggest 14th century Teutonic Order’s castle (after Malbork Castle). The castle was constructed by the Teutonic Knights here not by accident because the location on a narrow isthmus between two lakes allowed control transit roads and an effective defence of inland regions from attacks from the East. One more interesting consistent pattern could be seen in this fragment of the map: the distance between Ryn and Gižycko, where castles of the Teutonic Knights once were, is between 20-30km, the distance which a knight on horseback could cover in one day. Most of the towns are located in such way in former Prussia due a rule of the Teutonic Order according which the Teutonic Knights must travel due to security reasons only during daytime and spent night in an Order’s castle.