When the capital status was transferred to Helsinki from Turku in 1812, it was obvious that Helsinki would need a new centre to match its new status. Johan Albert Ehrenström designed the monumental lines of Helsinki’s new plan, and German-born Carl Ludvig Engel was persuaded to take on the architectural work. The new centre of autonomous Finland was arranged around the Senate Square. Engel designed the Cathedral as the focal point of the Senate Square and it is the principal landmark of the White City of the North.

Engel designed the church in 1818 but the construction work was postponed until 1830. The church was finally inaugurated in 1852, 12 years after Engel’s death. The extended process also introduced changes in the architecture: the main guard post at the base of the church was replaced with a monumental staircase. This led to the Senate Square below, opening up the church more towards the direction of the square. However, the main entrance remained on the Unioninkatu side where it still is.

After Engel’s death, his elegantly simple neoclassical design was embellished with decorative details to suit more modern tastes. Architect Ernst Lohrmann designed four smaller domes to surround the central dome of the church and statues of the 12 apostles were added to the apexes and corners of the roofline. Two pavilions were also added, one on each side of the monumental staircase. Some of Engel’s interior design features were also left out. This explains the rather obvious conflict between the decorative exterior and the austere interior.