Svartholma sea fortress was built by Swedish in the 18th century. Svartholma and near Loviisa land fortress were designated to defence strategic road from Turku tu Viborg and Sweden-Finland's eastern border against Russians. Svartholma construction started in 1748 and it was mostly completed in the 1760's. Svartholma was a typical bastion system including four bastions and an outer fortification.
Svartholma played an significant role in Russo-Swedish War 1788-1790. It was a naval stronghold for the Swedish fleet when it defeated Russians in Ruotsinsalmi battle. In the Finnish War (1808-1809) Svartholma was first time attacked by eastern enemies. The Russian artillery fired sporadically at the fortress, but no serious damage was inflicted. However, the Swedish officers, led by Carl Magnus Gripenberg decided to capitulate the fortress, almost without a fight on March 18, 1808.
Svartholma lost its strategical importance during the Russian period. It was used partly as a military base, and partly as a prison for Finnish prisoners. The empty fortress was largely destroyed by the British during the Crimean War (1855).
The Finnish National Board of Antiquities were restoring the fortress since the 1960s, and the work was finally ready in 1998. Today Svartholma is a popular tourist attraction with a museum and guided walking tours. It's possible to visit there by ferry-boat in summer time.
The castle of La Iruela, small but astonishing, is located on the top of a steep crag in Sierra de Cazorla, Segura y Las Villas Natural Park. From the castle, impressive views of the surrounding area and of the town can be enjoyed.
The keep dates from the Christian era. It has a square base and small dimensions and is located at the highest part of the crag.
There are some other enclosures within the tower that create a small alcázar which is difficult to access.
In a lower area of the castle, protected with defensive remains of rammed earth and irregular masonry, is an old Muslim farmstead.
After a recent restoration, an open-air theater has been built on La Iruela castle enclosure. This theater is a tribute to the Greek and Classic Eras and holds various artistic and cultural shows throughout the year.
The first traces of human activity in La Iruela area are dated from the Copper Age. An intense occupation continued until the Bronze Age.
Originally, La Iruela (like Cazorla) was a modest farmstead. From the 11th century, a wall and a small fortress were built on the hill to protect the farmers.
Around 1231, don Rodrigo Ximénez de Rada, Archbishop of Toledo, conquered La Iruela and made it part of the Adelantamiento de Cazorla. Over the Muslim fortress, the current fortress was built.
Once the military use of the fortress ended, it was used as cemetery.