Dubbed the "Polish Pompeii," Biskupin is the only known Iron Age settlement in Poland. It is also one of the most engaging attractions on the Piast Route. Though it is not connected to the Piast Dynasty, it is regarded as a key fragment in piecing together the origins of the country. The site was discovered by accident in 1933 by a teacher on a school excursion to Lake Biskupienskie. Wooden stakes sticking out of the lake caught his eye. Excavations revealed a network of well-preserved wooden foundations and defensive ramparts, and evidence indicates it was a fortified settlement of the Lusatian clan dating from around 550 B.C.
The present-day settlement you see is an impressive mockup of an Iron Age village. As the site is in the middle of nowhere, careful consideration has been given to make this a satisfying and complete afternoon out. There is a museum to give context to the place and, in season, daily demonstrations of pottery, archery, fire working with flint stone, and pony and leisure-boat rides. The archeological festivals in September showcase earlier civilizations -- from not just Europe, but also around the world, so don't be surprised to see a samurai gaiting by.
Biskupin can be stringed along with Gniezno as a day trip from Poznan.