Before the arrival of the Teutonic Knights, Koknese was the site of a wooden hill fort inhabited by the Balts. In 1209 Bishop Albert of Riga ordered the construction of a stone castle at the site, naming it Kokenhusen. For the first 50 years of its existence, Koknese was solely used as a defensive fort, but by 1277, Koknese had enough population to receive city rights. Koknese also became a member of the Hanseatic League thanks to its strategic location on the Daugava trade route.
The castle was heavily contested between Polish, Swedish and Russian forces in the 16th and 17th centuries. It changed hands many times, while the native inhabitants endured periodic slaughter, capture, and famine. In 1701, during the Great Northern War, Koknese was finally blown up by retreating forces to avoid the strategic castle falling into advancing Russian hands. The castle was never rebuilt and fell to ruin.
In 1900, a park was established around the castle ruins, and Koknese became a popular summer resort. The area was known for its scenic waterfalls, cliffs, and look-outs. In 1965, the Soviet government built Pļaviņas Hydro Power Plant in the town of Aizkraukle. The reservoir flooded the entire length of the Daugava to Pļaviņas. Koknese Castle, once sitting atop a high bluff, was placed at the river's edge, while the scenic Daugava valley was submerged.
References:The Church of St Donatus name refers to Donatus of Zadar, who began construction on this church in the 9th century and ended it on the northeastern part of the Roman forum. It is the largest Pre-Romanesque building in Croatia.
The beginning of the building of the church was placed to the second half of the 8th century, and it is supposed to have been completed in the 9th century. The Zadar bishop and diplomat Donat (8th and 9th centuries) is credited with the building of the church. He led the representations of the Dalmatian cities to Constantinople and Charles the Great, which is why this church bears slight resemblance to Charlemagne's court chapels, especially the one in Aachen, and also to the Basilica of San Vitale in Ravenna. It belongs to the Pre-Romanesque architectural period.
The circular church, formerly domed, is 27 m high and is characterised by simplicity and technical primitivism.