During the reign of Catherine the Great in the 1760s–1780s, the banks of the Neva were lined with granite embankments.
However, it was not until 1850 that the first permanent bridge across the Neva, Blagoveshchensky Bridge, was allowed to open. Obvodny Canal (dug in 1769–1833) became the southern limit of the city.
On March 12, 1918, the Soviets transferred the government to Moscow, to keep it away from the state border.
During the ensuing Civil War, in 1919 general Yudenich advancing from Estonia repeated the attempt to capture the city, but Leon Trotsky mobilized the army and forced him to retreat.
However, Saint Petersburg soon started to be built out according to a plan.
By 1716 the Swiss Italian Domenico Trezzini had elaborated a project whereby the city centre would be located on Vasilyevsky Island and shaped by a rectangular grid of canals.
In March 1917, during the February Revolution Nicholas II abdicated both for himself and on behalf of his son, ending the Russian monarchy and over three hundred years of Romanov dynastic rule.
The names of saints Peter and Paul, bestowed upon original city's citadel and its cathedral (from 1725—a burial vault of Russian emperors) coincidentally were the names of the first two assassinated Russian Emperors, Peter III (1762, supposedly killed in a conspiracy led by his wife, Catherine the Great) and Paul I (1801, Nicholas Zubov and other conspirators who brought to power Alexander I, the son of their victim).It remained the seat of the Romanov dynasty and the Imperial Court of the Russian Tsars, as well as the seat of the Russian government, for another 186 years until the communist revolution of 1917.In 1736–1737 the city suffered from catastrophic fires.The project was not completed, but is evident in the layout of the streets.In 1716, Peter the Great appointed Frenchman Jean-Baptiste Alexandre Le Blond as the chief architect of Saint Petersburg.