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 city walls of Avila were built in the 11th century to protect the citizens from the Moors. They have been well maintained throughout the centuries and are now a major tourist attraction as well as a UNESCO World Heritage Site. Visitors can walk around about half of the length of the walls.
The layout of the city is an even quadrilateral with a perimeter of 2,516 m. Its walls, which consist in part of stones already used in earlier constructions, have an average thickness of 3 m. Access to the city is afforded by nine gates of different periods; twin 20 m high towers, linked by a semi-circular arch, flank the oldest ones, Puerta de San Vicente and Puerta del Alcázar.