The Wenecja locality’s history is associated with the figure of Mikołaj Nałęcz of Chomiąża who in XIV century built a castle on the isthmus between the three lakes. As he saw his new residence similar to Venice in terms of its situation features, he named the site Wenecja (Polish for ‘Venice’). Wenecja was granted municipal rights in 1411 and maintained them into 16th century. Their loss was caused by changed political arrangements, as combined with a lessened importance of the castle in the strategic map of Poland after 2nd Peace Treaty of Toruń (Thorn) in 1466.

The castle was built by Mikołaj Nałęcz of Chomiąża around 1395, as a stone edifice intertwined with brick elements, founded on a square plan, side length 33 m. Its convenient situation between the three lakes has increased its value as a fortress. The castle was a notorious place for almost the entire period of its existence. In the initial years, this was so because of Mikołaj Nałęcz who, being a judge of Kalisz, had made a name for himself due to extremely cruel verdicts he was passing, which won him the nickname of the Wenecja Devil. Others believe that the sobriquet was coined in the course of a cruel civil war that rumbled through the area of Wielkopolska in 1382 to 1385. As Wenecja was taken over by the Gniezno bishopric, the castle was last upgraded in 1435, the works being led by Gregor of Ossek, brought along from Moravia. The castle was surrounded then with an additional pentagonal wall and a dirt wall; moreover, the stronghold was furnished with canons launching stone balls of diameters 3.4cm to 25cm. At that time, a gaol for priests sentenced by an ecclesial court was in operation there. As the 2nd Peace of Thorn was entered into in 1466, the castle ultimately lost its military significance and its slow decline is dated ever since.

Today, the castle is a picturesque ruin to which tourists visiting the nearby Narrow-Gauge Railway Museum and sightseeing other attractions on the Piast Route willingly pay visits.