In 1808, Russia invaded Finland. One year later Finland was ceded to Russia, and Helsinki was destroyed by a huge fire.
More importantly, in 1812, Czar Alexander I declared Helsinki the new capital of the Grand Duchy of Finland.
All this paved the way for a new town plan drawn up by Johan Albrecht Ehrenström. New buildings were designed by the Prussian architect Carl Ludvig Engel.
When Engel first arrived, Helsinki had a mere 4,000 inhabitants. By the time he died in 1840, the figure had risen to 18,000, and the new townscape was dominated by light-coloured, plastered brick buildings and low, timbered log houses.
The centrepiece was the new Senate Square around which were arranged the key institutions of government, religion, and higher learning.
On the northern flank soared the Lutheran church of St. Nicholas, or Helsinki Cathedral.
To this day, travellers arriving in Helsinki by sea are faced with this historic, Empire-style city centre.
The wooden houses that once surrounded it have long since disappeared.
However, the street layout between the Senate Square and Eteläsatama (the South Harbour) and Kauppatori (the Market Square) dates from the Swedish era, as do some of the buildings, although many of the facades have been altered.
Many of the characteristically yellow buildings you see in Helsinki date from this era, too.