The castle of Toolse was built in 1471 by the Livonian Order as defence against pirates sailing in the Gulf of Finland. During the Livonian War it changed hands several times, was apparently destroyed and later rebuilt. In 1581 French mercenary Pontus de la Gardie captured the castle for Sweden from Russia which had held it since 1558. The castle was destroyed again during the Great Northern War, ever since which it has laid in its current state of ruin.
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.