The Sandarmokh forest massif near Medvezhyegorsk (12km from Medvezhyegorsk towards Vologda)is the biggest shooting range and burial ground in the Russian North-West. About 10 thousand are buried here: 3500 Karelians, 4500 White to Baltic sea canal workers, and 1000+ political prisoners from Solovki, all shot in 1937-1938, at the height of purges. Now it is a memorial cemetery.
More here >> (English) and here >> (Russian).