Church of the Holy Trinity

Helsinki Cathedral is a cathedral of the Evangelical Lutheran Church of Finland located in the centre of Helsinki. It was built between 1830 and 1852 when Finland was part of the Russian Empire (1809-1917) and was called St. Nicholas' Church. As early as 1818, Carl Ludwig Engel, who worked on the design of the whole square, drew the first plans of the church and refined them over a decade. The cathedral replaces the former Ulrika Eleonora church. The church did not officially become a cathedral until 1959 when the Helsinki Diocese was established.

The Cathedral of the Assumption, or Uspenski Cathedral, is the cathedral of the Orthodox Diocese of Helsinki. It was built by order of Emperor Alexander II of Russia between 1862 and 1868. It was designed by the architect Alexis Gornostaiev (1808-1862), one of the founders of the Russian Revival architecture. The crypt hosts a variety of events, including exhibitions and lectures on ecclesiastical art and ecclesiastical artefacts.

The Old Church of Helsinki is the oldest church in Helsinki city centre, completed in 1826 by the architect Carl Ludvig Engel. The Old Church was originally intended only as a temporary solution when the 18th century Ulrika Eleonora Church, which was replaced by Helsinki Cathedral, was demolished to make way for the Senate square. Due to the temporary character, the old church was built of wood and without bells. The Old Church is surrounded by the Old Church Park, which was a former cemetery.