Hämeenlinna means Häme Castle, so it’s no surprise that this bulky, twin-towered, red-brick fortress is the town’s pride and most significant attraction. Construction was begun in the 1260s by the Swedes, who wanted to establish a military redoubt against the power of Novgorod. It was originally built on an island, but the lake receded and necessitated the building of new walls. It never saw serious military action and, after the Russian takeover of 1809, was converted into a jail.
The interior has a modern exhibition annex displaying period costumes and furniture that's tacked on to the original bare-roomed building. Free multilingual guided tours leave every hour in summer – book these ahead outside of summer (a charge will apply).
