Short answers, pulled from the story.
Tsar Peter the Great laid the cornerstone of the Peter and Paul Fortress on the 27th of May 1703. He chose Zayachy Island at the mouth of the Neva River to secure a foothold against Swedish forces during the Great Northern War.
The city was officially renamed Leningrad five days after Lenin's death on the 21st of January 1924. This change followed the earlier renaming to Petrograd in 1914 to remove German-sounding words, and it honored the communist leader who died that month.
The blockade lasted 872 days stretching from the 8th of September 1941 to the 27th of January 1944. More than one million civilians died during this period mostly from starvation and exposure while food supplies reached the city only through the Road of Life across Lake Ladoga when the lake froze.
A city-wide referendum held on the 12th of June 1991 restored the original name Saint Petersburg with 55% of voters supporting the change. Sixty-six percent of total votes went to Anatoly Sobchak who became the first directly elected mayor of the city.
Completed in 2019 the tower stands 462.5 meters tall making it the tallest building in Russia and Europe outside Moscow. Construction began in 2012 on the Lakhta Center site northwest of the city center after President Dmitry Medvedev intervened in December 2010 regarding a previous project.