St. Petersburg was NOT built on a swamp!
The Russian tsar picked the Neva River delta for the construction of the city. This river connects Lake Ladoga - the second largest lake of Russia - with the Baltic Sea. In the 8th-13th centuries, the Neva River hosted the trade route "from the Varangians to the Greeks" - from Scandinavia to the Byzantine Empire.
A popular modern meme about Petersburg being built on a swamp
In the Finnish language, 'Neva'