Węgorzewo weNgo'żewo (until 1946 Węgobork; Angerburg, Ungura) is a tourist town on the Angrapa River in northeastern Poland, within the historical region of Masuria. It is the seat of Węgorzewo County in the Warmian-Masurian Voivodeship and is located not far from the border with Russia's Kaliningrad Oblast. Lake Mamry is close to the town. The town's names in different languages are derived from local names for European eels, which used to live in the area in great numbers. The German name Angerburg () is derived from the Old Prussian word for eel, Anger, which the German Teutonic Knights appropriated after conquering the Old Prussians. The Polish name Węgorzewo (and the older Węgobork) is derived from Węgorz, while the local Lithuanian names Ungura and Unguris comes from Ungurys. A Lithuanian variation is Angerburgas. The town was first mentioned in a 1335 chronicle as Angirburg, or "eel castle", a settlement of the Teutonic Knights with a block house, a palisade, and a watchtower. A 1341 document reported that the Teutonic Order had bestowed land on the river Angerapp (Angrapa) upon twelve Old Prussians for their loyal service. The Grand Duke of Lithuania, Kęstutis, destroyed the castle in 1365, although it was rebuilt in 1398. The completion of the stone castle Angerburg allowed the Teutonic Knights to increase development of the surrounding countryside. In 1454, the region was incorporated by King Casimir IV Jagiellon to the Kingdom of Poland upon the request of the anti-Teutonic Prussian Confederation. After the subsequent Thirteen Years' War, since 1466, it formed part of Poland as a fief. The land around the castle began to be settled by the end of the 15th century. As it was primarily farmland, the Lake Mamry was blocked up to allow the construction of a watermill. Ca. 1510 a locality known as Neudorf ("new village") or Gerothwol had developed near the Angerburg. After the foundation of the Duchy of Prussia as a fief of the Kingdom of Poland in 1525, Angerburg/Węgobork became the seat of a district head.