Vyborg Castle is a fortress in Vyborg, Russia. It was built by the Swedes during the Middle Ages around which the town of Vyborg evolved. The castle became the stronghold of the Swedish realm in the Karelian region. Throughout the centuries, it was the first defense of the kingdom against the Russians. Its military and strategic status in the late Middle Ages was second only to the fortified capital Stockholm. Currently it serves as the site of Vyborg Regional Museum.

Vyborg is a town and the administrative center of Vyborgsky District in Leningrad Oblast, Russia. It lies on the Karelian Isthmus near the head of Vyborg Bay, 130 km northwest of St. Petersburg, 245 km east of the Finnish capital Helsinki, and 38 km south of Russia's border with Finland, where the Saimaa Canal enters the Gulf of Finland. The most recent census population of Vyborg is 72,530 (2021 Census).