A reported German WWII-era ringstand (Tobruk) bunker, designated DF-13, located near St. Petersburg, Russia. The structure's existence and specific details are not confirmed by the provided historical sources. The region around St. Petersburg saw significant military activity during World War II, including the Siege of Leningrad, and German forces constructed various field fortifications in the area during their advance.
However, without corroborating archaeological, archival, or historical records, the precise nature, construction date, and operational history of this specific site remain unverified.