Sennaya Square, Public square in central Saint Petersburg, Russia.

Sennaya Square is a public plaza in central Saint Petersburg located at the intersection of Garden Street, Moskovsky Prospekt, and Grivtsova Lane. The square serves as a central crossroads where several neighborhoods meet and is bordered by buildings from different periods.

The square was established in 1737 as a marketplace for hay, firewood, and livestock trading, becoming a commercial center for merchants and farmers. Its origins as a trading location have shaped its role in the city to this day.

The square's nickname, "the belly of Petersburg" (by analogy with "the belly of Paris"), reflects its role as a crowded market crossroads. Fyodor Dostoevsky set scenes of Crime and Punishment in the surrounding slums, and the name Sennaya comes from the hay sold here from the 1730s.

Three metro stations meet here: Sennaya Ploshchad, Sadovaya and Spasskaya, and buses and marshrutkas stop on the square. Trams ran here until 2010; a fragment of the rails is kept as a historical mark. The square is a broad open crossing, so allow time to orient yourself among the converging streets.

During the cholera outbreak of 1831, the square became the site of public demonstrations as residents protested against foreign doctors. This event reveals how social tensions found an outlet at this central location.