Shlisselburg, formerly Oreshek (Орешек) (1323–1611) and Petrokrepost (Петрокрепость) (1944–1992), is a town in Kirovsky District, Leningrad Oblast, Russia, located at the head of the Neva River on Lake Ladoga, 35 kilometers (22 mi) east of St. Petersburg. Population: 13,170 (2010 Russian census); 12,401 (2002 Census); 12,589 (1989 Soviet census).

The Neva is a river in northwestern Russia flowing from Lake Ladoga through the western part of Leningrad Oblast to the Neva Bay of the Gulf of Finland. Despite its modest length of 74 kilometres (46 mi), it is the fourth-largest river in Europe in terms of average discharge.