The church was originally built from 1830-1852 as a tribute to the Grand Duke of Finland, Nicholas I of Russia. It was also known as St. Nicholas Church until the independence of Finland in 1917. The cathedral was built on the site of the smaller Ulrika Eleonora Church, which was dedicated to its patroness, Ulrika Eleonora, Queen of Sweden.
The church’s plan is a Greek cross, symmetrical in each of the four cardinal directions, with each arm’s façade featuring a colonnade and pediment. Surrounded by four smaller domes, the building is in the neoclassical style. It was designed by Carl Ludvig Engel as the climax of his Senate Square. The building was later altered by Engel’s successor Ernst Lohrmann.