Mannerheimintie, (in Swedish Mannerheimvägen, colloquially Mansku) can be considered the main street of Helsinki – another contestant for that title would be Aleksanterinkatu, which it crosses.
Mannerheimintie translates to Mannerheim road and got its current name from Marshal Mannerheim (1867–1951). The street of 5.5 km is the main north-south route west of the railway and has been a major thoroughfare for centuries.
Already in the 17th century a road existed here connecting settlements on the Helsinki peninsula to the King’s Road, the main east-west road in Finland back then. With the Russian rule after the Napoleonic Wars, Helsinki became the capital of Finland and a new zoning plan was drawn up. The southernmost part of present-day Mannerheimintie was named Henriksgatan (in Swedish, which aside of Russian was the administrative language then – its Finnish name would be Heikinkatu) after then-Secretary of State Robert Henrik Rehbinder. Henriksgatan was divided into a western and eastern street with a narrow park between them, this is where the tram today runs. North of the Turku barracks (where Lasipalatsi now is), the street was named Åbovägen (Sw.)/Turuntie (Fi.), i.e. Turku Road.
In the 1850s Turuntie was renamed Västra chausséen (Sw.)/Läntinen viertotie (Fi.) (Western Chaussee), whereas present-day Hämeentie the other main road leading north-east from Helsinki was renamed Östra chausséen (Sw.)/Itäinen viertotie (Fi.) (Eastern Chaussee) and both were widened and covered with gravel to the city border, in the case of the Western Chaussee, to Töölöntulli. Here voyagers had to pay a toll to cross into the city. To this day these remain important arteries into central Helsinki.
In 1928 the “chaussee” part was once again named Turuntie, and in 1935 the two Henrikinkatu streets were merged into one as the trees were cut down and the park transformed into lanes for trams to accommodate more traffic in the quickly growing capital. The street got its present name during WWII in 1942, when Heikinkatu and Turuntie were administratively turned into one street and renamed Mannerheimintie after commander-in-chief Marshal Carl Gustaf Emil Mannerheim on his 75th birthday.
Today Mannerheimintie remains a lively street passing many of the city’s most famous attractions, and can be considered Helsinki’s Broadway.