Short answers, pulled from the story.
Saint Petersburg was founded on the 27th of May 1703 when Russian forces captured the wooden fortress Nyenskans and began constructing a new citadel on Zayachy Island. Tsar Peter the Great chose this swampy delta of the Neva River to build a capital that would serve as a window to Europe.
Saint Petersburg is called the Venice of the North because it is built on swamp and water with an intricate web of canals and waterways. The city features granite embankments and neoclassical facades that reflect its unique hydrology and architectural history.
German forces besieged Leningrad for 872 days from the 8th of September 1941 to the 27th of January 1944. More than one million civilians were killed during this period mainly from starvation and the population dropped from 3 million to less than 600,000.
The name of Saint Petersburg was officially restored on the 6th of September 1991 following a city-wide referendum held on the 12th of June 1991. During that referendum 55% of voters supported restoring the original name while 43% supported keeping the name Leningrad.
The White Nights phenomenon in Saint Petersburg occurs from mid-May to end-July when it does not get darker than nautical twilight due to the city's northerly location at approximately 60 degrees north latitude. This natural phenomenon arises from the city's closeness to the polar region.