Meyendorff Castle or Meiendorf Castle (Майендорф or Майндорф) is a Châteauesque architectural extravaganza constructed at the turn of the 20th century in Barvikha near Moscow to Pyotr Boytsov's designs as a private residence of the Meyendorff family (a cadet line of the Baltic German noble house of Uexküll). After the outbreak of the Great War the owners of the castle left Russia for abroad.
After the October Revolution the castle was occupied by Vladimir Lenin and other Bolshevik leaders. In 1935 the grounds were declared a high-profile, exclusive sanatorium. Mikhail Bulgakov, Sergey Korolyov and Yuri Gagarin were among those who vacationed at Barvikha. There is also a World War II cemetery marked by Yevgeny Vuchetich's miniature copy of his Mamayev Monument.
In the 21st century Barvikha Castle has been designated a country residence of the President of Russia. It was there that the Meyendorff Declaration of 2008 was signed by the leaders of Armenia and Azerbaijan.