Catherinethal ("Catherine's valley") is a Petrine Baroque palace of Catherine I of Russia in Tallinn. It was built after the Great Northern War to Nicola Michetti's designs by Gaetano Chiaveri and Mikhail Zemtsov. In the 20th century the Estonian version of the name, Kadriorg, gained currency and came to be applied to the surrounding district.
After the successful siege of Reval in 1710 Peter the Great of Russia bought a Dutch-style manor house at Lasnamäe for his wife Catherine. The house today is the result of a drastic renovation ordered by Nicholas I of Russia in 1827.
The new palace was started on 25 July 1718. Peter and Catherine visited the unfinished residence on several occasions, but after the emperor's death in 1725 Catherine showed no interest in the seaside property. The great hall with Catherine's initials and profuse stucco decor (attributed to Heinrich von Bergen) survives, but many other interiors have been altered. The gardener Ilya Surmin was responsible for the flower garden with two fountains and the so-called mirage garden on several levels. The layout of the park shares similarities with that of Strelna.
The palace currently houses an art gallery. The KUMU Museum is sited in the park.
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.