Originally built as an Eastern Orthodox church in 1854. At that time Suomenlinna was a Russian garrison. The church survived heavy bombardment from British and French navies in 1855 or at least any historical source doesn't mention that it would have been damaged.
When Finland declared independence from Russia in 1917 the church was converted to Evangelical Lutheran. During extensive renovations from 1927 to 1929 a lighthouse was added to central dome.
The lighthouse signals four short glints and then keeps a short pause. This is Morse-symbol for H - Helsinki.
