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:The Roman Theatre of Mérida is a construction promoted by the consul Vipsanius Agrippa in the Roman city of Emerita Augusta, capital of Lusitania (current Mérida). It was constructed in the years 16 to 15 BCE. One of the most famous and visited landmarks in Spain, the Roman Theatre of Mérida is regarded as a Spanish cultural icon and was chosen as one of the 12 Treasures of Spain.
The theatre has undergone several renovations, notably at the end of the 1st century or early 2nd century CE (possibly during the reign of Emperor Trajan), when the current facade of the scaenae frons was erected, and another in the time of Constantine I (between 330 and 340), which introduced new decorative-architectural elements and a walkway around the monument. Following the theatre"s abandonment in Late Antiquity, it was slowly covered with earth, with only the upper tiers of seats (summa cavea) remaining visible.