The first settlements appeared in Gniew at the beginning of the 7th century. However, the Teutonic Order invasion in the 13th century altered the course of history, and the city got hold of a powerful defensive fortress. Back then, the town of Gniew was called Mewe, hence the name of the castle, a brick perfectly-rectangular structure built in more than 40 years. A century later, the castle got a spacious chapel and a new eastern gate, though it also had many losses as a result of numerous medieval wars between the Teutonic knights and Polish troops. Mewe and the Polish governor did not rule for long after the capitulation of the Teutons. They were replaced by the Swedish invaders who, afterward, became prisoners of war and were kept in this castle.

Throughout the whole history, Mewe Castle remained a desirable trophy due to its strategic location. On one side, fights and conquests had a devastating effect on the ancient fortress. On the other side, thanks to different rulers, the powerful citadel acquired new constructions and interiors traditional for a conquering state. At still other times, the castle had a grain barn and a prison for German invaders. There were also sad times of oblivion and almost complete destruction of the once formidable fortification.

Today, all structures in the castle have been restored. There are different international festivals of medieval culture, pottery and art forgery, and legendary jousting tournaments. But the main event of the year annually takes place in the castle at the end of summer. Travelers from all over the world come to the ancient castle to enjoy a grand spectacular show dedicated to the battle of 1626, the fight between the cousins, Gustav II Adolf of Sweden and Sigismund III of Poland, for control of the Vistula estuary.