What is "goplo"

Gopło is a lake in Kuyavian-Pomeranian Voivodeship, north-central Poland, near the city of Gniezno. It gives its name to the protected area called Gopło Landscape Park.

In early Middle Ages, the shores of Lake Gopło were home to a West Slavic tribe of Goplans. At the northern end of the lake stands the "Mouse Tower" of Kruszwica. Its name derives from a legend of the corrupt Prince Popiel, whose fled to the tower from his rebelling population, and was devoured there by mice. Some historians and archaeologists consider the area the heart of the first state of the Polans, the "founding" tribe of Poland.