Sparrow Hills
Since 1830 Mamonov was kept in strict isolation at Vassilyevskoye manor at Sparrow Hills, which had expressly been purchased from Prince Yusupov. In consequence of the long detention there of Count Mamonov it was named "Mamonovian Dacha" by the Muscovites. "Treatment" and abuse by the turnkeys did not remain without effect: People, who met the count during the 1840-1860 period, remember him as a lunatic suffering from delusions of persecution and grandeur. He died from gangrene caused by the constant wear of perfumed shirts. He was buried at the Donskoy Monastery at Moscow. With him the (first) comital line of the house of Dmitriev-Mamonov expired.