The history of Suomenlinna Church dates back to the establishment of Viapori Fortress in 1748. When Sweden lost the entire territory of Finland to Russia in 1809, plans were made to establish a church on the fortress grounds. The initial designs for the church were drawn up by Konstantin Thon in 1838, but construction officially began in 1849. The church was completed in 1854. Initially named the Church of St. Alexander Nevsky, it was considered Finland's finest Orthodox church at the time, representing the pinnacle of architecture.
After Finland gained independence, the appearance of the church was altered, and it was converted into a Lutheran church according to the plans of Einar Sjöström. It was consecrated as a Lutheran church in 1929 and served as a garrison church until the Finnish Defense Forces handed over the building to the Evangelical Lutheran Parishes of Helsinki in 1960. After extensive renovations, the church was re-consecrated in February 1964.
The church tower houses a lighthouse serving maritime and aviation traffic, emitting four consecutive flashes representing the letter 'H' in Morse code, signifying Helsinki