Peter the Great patterned the city after Amsterdam, and even though St Petersburg is newer than New York by almost 100 years, in some places it feels a thousand years old — a few buildings seem to be a cross between Roman ruins and German palaces. The building walls, usually between three and four feet thick, host basement cafés and restaurants where you can’t get a mobile phone signal. The walls are moist, and smell like rivers, because the city was built on marshland.