Few of the world's great cities have experienced such fluctuations in fortune as Leningrad in the present century. On the eve of World War I St Petersburg, as the city was then known, was a flourishing port and industrial centre, capital of the Russian Empire, a city of over two million people. The war, the two revolutions of March and November 1917, the ensuing Civil War, and the loss of the city's capital status in 1918 had a catastrophic effect. By 1921, the population had fallen to 830,000. It was not to regain its pre-war population until the early 1930s. In the late 1920s, however, with the launching of Stalin's campaign of industrialisation, Leningrad's economy revived and expanded, and migration into the city resumed its pre-revolutionary vigour. By 1939, Leningrad's population stood at over three million people. Disaster struck once more during World War II when the city withstood a 900-day siege and the population fell to a fraction of its former level-a level it was not to reach again until the 1960s. Since the war Leningrad has experienced first a gradual revival from wartime ruin, and then renewed progress in its development as a socialist city. That progress has brought many problems to the fore, not a few of which derive from the uneven nature of Leningrad's development during the twentieth century.