How did the Leningrad siege take three years?

>>3259558
I'm not sure what you are implying but the german deliberatly let the civilians die by making a siege instead of storming the city.

The Soviets were willing to defend the place tooth and nail, the Germans only had enough troops in the North to siege it instead of fully assault it (they were more busy with Moscow, Stalingrad, etc.), and the Soviets just weren't going to surrender to the sieging forces either.

Germans didnt have enough resources to invest in fully capturing it
Russia was preoccupied in driving out the axis elsewhere and also with the Finns near Karelia

>>3259558
basically one day they started it and the end came three years later.

It's not that unusual. Sarajevo was besieged even longer not 25 years ago.

Finns didn't want to assault the city and the Germans didn't have the manpower to storm another large city at the time so they just waited it out.