The ruins of the former Teutonic Order Case from 14th century are situated on ul. Zamkowa. In a very distant past, the first watchtower of Yotvingans was built there.
Between 1398 and 1406 the knights of the Teutonic Order built the wooden castle and then – a castle of stone. The building was supervised by the then Grand Master of the Teutonic Order – Urlich von Jungingen. After the secularization of the order in 1525, the castle of Ełk became a seat of the local government officer and then – a court of justice. The great fire in 1833 extorted the renovation which had fundamentally changed the appearance of the former stronghold. In 19th century the island was linked with the land by a dike and a bridge, and the castle served as a women’s prison. Presently it had completely lost its original style and waits for renovation. According to a legend, under the bed of the Lake Ełckie, there is an underground tunnel, connecting the castle with the town. It is said that this tunnel enabled the citizens to find a shelter in the walls of the castle when the Tatar’s raided the town during the Deluge.