Suomenlinna ("Sveaborg", "Viapori") sea fortress is a UNESCO World Heritage Site and one of Finland’s most popular tourist attractions. The construction of the fortress started by the king of Sweden in 1748 as protection against Russian expansionism. Suomenlinna was planned to be a principal base for naval military operations and the general responsibility for the fortification work was given to Augustin Ehrensvärd. The construction phase lasted for over four decades. During this time six islands were fortified to provide a safe harbor and dock for the archipelago fleet in Finland.
In the Finnish War (1808-1809) Russians easily took Helsinki in early 1808 and began bombarding the fortress. Its commander, Carl Olof Cronstedt, negotiated a cease-fire, and when no Swedish reinforcements had arrived by May, Suomenlinna surrendered with almost 7,000 men. After taking over the fortress the Russians set about on an extensive building program, mostly extra barracks, but also extending the dockyard and reinforcing to the fortification lines.
During the Crimean War in 1855 a combined Anglo-French fleet bombarded Viapori for two days in August. At this point, the repair work was nowhere near complete, and Viapori sustained heavy damage in the bombardment. The next stage in the arming of Suomenlinna and the Gulf of Finland came in the build-up to World War I. The fortress and its surrounding islands became part of "Peter the Great's naval fortification" designed to safeguard the capital, Saint Petersburg. The fortress became part of an independent Finland in 1917, following the Russian Revolution.
After the Finnish Civil War, a prison camp existed on the island. About 6000 red prisoners were held in Suomenlinna. Many of them were executed by the white army and others died of disease due to the poor conditions in the fortress.
Suomenlinna is today one of the most popular tourist attractions in Helsinki as well as a popular picnicking spot for the city's inhabitants. A number of museums exist on the island, as well as the last surviving Finnish submarine, Vesikko.
The Mosque–Cathedral of Córdoba, also known as the Great Mosque of Córdoba and the Mezquita is regarded as one of the most accomplished monuments of Moorish architecture.
According to a traditional account, a small Visigoth church, the Catholic Basilica of Saint Vincent of Lérins, originally stood on the site. In 784 Abd al-Rahman I ordered construction of the Great Mosque, which was considerably expanded by later Muslim rulers. The mosque underwent numerous subsequent changes: Abd al-Rahman II ordered a new minaret, while in 961 Al-Hakam II enlarged the building and enriched the Mihrab. The last of such reforms was carried out by Almanzor in 987. It was connected to the Caliph"s palace by a raised walkway, mosques within the palaces being the tradition for previous Islamic rulers – as well as Christian Kings who built their palaces adjacent to churches. The Mezquita reached its current dimensions in 987 with the completion of the outer naves and courtyard.
In 1236, Córdoba was conquered by King Ferdinand III of Castile, and the centre of the mosque was converted into a Catholic cathedral. Alfonso X oversaw the construction of the Villaviciosa Chapel and the Royal Chapel within the mosque. The kings who followed added further Christian features, such as King Henry II rebuilding the chapel in the 14th century. The minaret of the mosque was also converted to the bell tower of the cathedral. It was adorned with Santiago de Compostela"s captured cathedral bells. Following a windstorm in 1589, the former minaret was further reinforced by encasing it within a new structure.
The most significant alteration was the building of a Renaissance cathedral nave in the middle of the expansive structure. The insertion was constructed by permission of Charles V, king of Castile and Aragon. Artisans and architects continued to add to the existing structure until the late 18th century.
The building"s floor plan is seen to be parallel to some of the earliest mosques built from the very beginning of Islam. It had a rectangular prayer hall with aisles arranged perpendicular to the qibla, the direction towards which Muslims pray. The prayer hall was large and flat, with timber ceilings held up by arches of horseshoe-like appearance.
In planning the mosque, the architects incorporated a number of Roman columns with choice capitals. Some of the columns were already in the Gothic structure; others were sent from various regions of Iberia as presents from the governors of provinces. Ivory, jasper, porphyry, gold, silver, copper, and brass were used in the decorations. Marvellous mosaics and azulejos were designed. Later, the immense temple embodied all the styles of Morisco architecture into one composition.
The building is most notable for its arcaded hypostyle hall, with 856 columns of jasper, onyx, marble, granite and porphyry. These were made from pieces of the Roman temple that had occupied the site previously, as well as other Roman buildings, such as the Mérida amphitheatre. The double arches were an innovation, permitting higher ceilings than would otherwise be possible with relatively low columns. The double arches consist of a lower horseshoe arch and an upper semi-circular arch.