FTP, name this lake of the Karelian Isthmus that is drained to the Gulf of Finland by the Neva River and is the largest lake in Europe.
Shlisselburgh and Sortavala are two cities on its shores, and it contains over 600 islands.  The largest of those islands is home to a monastery that was evacuated to a nearby country just before the Continuation War, but which has recently returned to the island of Valaam.  The majority of its water comes from three sources: Lake Ilmen, via the Volkhov River; Lake Saimaa, via the Vuoksi River; and Lake Onega, via the River Svir.  FTP, name this lake of the Karelian Isthmus that is drained to the Gulf of Finland by the Neva River and is the largest lake in Europe.
Shlisselburgh and Sortavala are two cities on its shores, and it contains over 600 islands.  
Lake Ladoga