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 World War I the owners of the castle left Russia.
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.