Oulu castle (Uleåborg) was built in 1590 for a stronghold to Swedish soldiers on their way to fight against Russian Karelia. The castle was mostly made of wood and earth walls. There probably was an earlier medieval castle on the same location. The Russian Sophia Chronicle has recorded that men from Novgorod tried to conquer a new castle in the Oulu River delta in 1377 but were unsuccessful. King of Sweden, Charles IX ordered to rebuild the castle in 1605. Old wooden parts were demolished and a new wall was built around the castle island.
Russians burned down wooden parts of the Oulu castle during the Great Northern War in 1715. Final destruction occured in 1793, when thunderstorm set the castle on fire and gunpowder magazine exploded.
Wooden constructions on the remaining powder magazine date from 1875 when the Oulu School of Sea Captains built their observatory on the site. The building has been a cafeteria since 1912 with a small exhibition on the castle history.
References:House of the Blackheads (Melngalvju nams) is a building situated in the old town of Riga. The original building was erected during the first third of the 14th century for the Brotherhood of Blackheads, a guild for unmarried German merchants in Riga. Major works were done in the years 1580 and 1886, adding most of the ornaments.
The structure was bombed to a ruin by the Germans June 28, 1941 and the remains demolished by the Soviets in 1948. The current reconstruction was erected from 1995 to 1999. Today the House of Blackheads serves as a museum and sometimes concert hall.