The ruins of the Koknese Castle are found where the Daugava and Pērse rivers flow together. The castle, which is on a floodplain, was built for the bishopric of Rīga in 1209, and it replaced an ancient Latvian castle that was made of wood. The castle was blown up by Saxon forces in 1701. A visitors centre is near the ruins, and there you can carve a Medieval coin or rent a boat to sail down the Daugava. Make sure to stroll through the Koknese park, which is alongside the ruins.