Masurians began to settle the region in the 16th century while it was part of the Duchy of Prussia, a fief of the Kingdom of Poland. Systematic settlement began in 1565, while the town was officially founded by Caspar von Nostitz on May 15, 1570. Located at a profitable location on the crossing of several trade routes near the Prussian border with Lithuania, Gołdap grew rapidly. Its coat of arms depicts the House of Hohenzollern and Brandenburg, while the letter "S" stands for Sigismund II Augustus, King of Poland, who was the suzerain of the region. In 1656, during the Polish-Swedish War, Polish troops under command of Dymitr Jerzy Wiśniowiecki were stationed in Gołdap.