Istanbul's 20th Civil Court has annulled all ownership claims regarding the Tarabya villa on the Bosphorus.
The court also prohibited the sale of the property and restricted its use.
Lawyer Selim Sarıibrahimoğlu, representing the Russian side, said they will appeal the decision, including to the Constitutional Court.
The dispute has been ongoing since 2008, involving Russia, Turkey, and heirs of Nikolay Svechin.
