After the Sweden's defeat in Russo-Swedish War 1741-1743 (also known as the Hats' Russian War) eastern border of Finland was moved to west. Important fortresses of Hamina, Lappeenranta and Savonlinna were left to Russian side of border.
The city of Loviisa was established in 1745 to handle a international commerce in Finland. Planning of the new fortification system started concurrently, because Loviisa was located alongside the strategic road from Vyborg to Turku. The parliament accepted the plan of twin fortresses in 1747: one in Loviisa city to protect the road and another to Svartholma island to defence Loviisa from the sea. Building of the Loviisa fortress started in 1748, but the plans were never completed. The ground was too muddy for heavy stone walls and the Crown had continuous lack of money. Building was interrupted in 1757 and the king Gustav III ordered to stop the construction permanently in 1775. Loviisa fortress didn't see any battle. In the Finnish War 1808-1809 it surrended to Russians without fighting, because people of Loviisa were afraid of the destruction of the city.
Nowadays there remains two completed bastions, Rosen and Ungern. Renovation started in the 1960's and Ungern is mostly renovated. Rosen is still uncompleted and mostly ruined.
Vufflens castle was built in 1425 on the site of a previous medieval castle by Henri de Colombier. It is the most significant example of a small group of fortified Romandy castles from the middle ages, characterised above all by its brick construction. In 1530, it was set on fire by Bernese troops. In 1641 it was acquired by the de Senarclens family. The castle is currently privately owned and cannot be visited.
A pleasant 30 minute-walk through the vineyards between Vufflens-le-Château and Denens, offers a stunning view of this magnificent castle, the lake and the Mont-Blanc.