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 Church of the Holy Trinity is an Orthodox church designed by Carl Ludvig Engel, consecrated in 1827. The church is Empire style and serves the large Russian-speaking minority of Orthodox in Helsinki, partly because the other Orthodox churches in the city have held their services in Finnish. The top of the church's bell tower was originally made of wood, but twenty years after its construction it was rebuilt in the present stone when new heavy bells were added to the church.
The German church was built in 1864 and designed by Harald von Bosse and C. J. von Heideken in the neo-gothic style. The church burnt down in 1958 and was then repaired according to the plans of architect O. Hansson. Between 1997 and 2001 the church underwent a major renovation, modification and extension of the buildings, designed by architects Juha Leiviskä and Rosemarie Schnitzler.