The hill fort in Rapola Ridge the largest ancient fort in Finland. As is the case with most hill forts in the Baltic area not much is known about its exact origins or purposes. One postulation is that it was built by the inhabitants in their struggles against invading Novgorodians and Swedes. According to excavations, the fort seems to have been in operation at least during the 13th and 15th centuries. Parts of it may be even earlier, since the area has been inhabited already in the 7th century. The medieval Sääksmäki church is located nearby, and the oldest signs of farming in Finland (dated 200 BCE) is also found there.
The fort was partly constructed on a natural hill that was eventually entirely fortified. The fort was 400 meters long and 200 meters wide. Remains of the earth walls are still visible. There is a guided path through the hill fort beginning at the car park of Voipaala manor.
