The Hakaniemi market square is a market square located in Hakaniemi, Helsinki, Finland, opened in 1897. Throughout its history, there have been numerous Vappu marches and demonstrations starting from the square, and it is an integral part of the history of the Finnish workers' movement. Many buildings near the square have been owned by Elanto and trade unions. The most famous buildings near the square are the circular Ympyrätalo office building and the Hakaniemi market hall.