Hagia Sophia is a mosque, museum and former church serving as a major cultural and historical site in Istanbul, Turkey. The current structure was built by the Byzantine emperor Justinian I as the Christian cathedral of Constantinople between 532–537. As the episcopal see of the ecumenical patriarch of Constantinople, it remained the world's largest cathedral for nearly a thousand years, until the Seville Cathedral was completed in 1520. It is considered the epitome of Byzantine architecture. Hagia Sophia became the quintessential model for Eastern Orthodox church architecture, and its architectural style was emulated by Ottoman mosques a thousand years later.
The site was an Eastern rite church from AD 360 to 1453, except for a brief time as a Latin Catholic church between the Fourth Crusade in 1204 and 1261.
After the fall of Constantinople to the Ottoman Empire in 1453, it was converted to a mosque by Mehmed the Conqueror and became the principal mosque of Istanbul until the 1616 construction of the Sultan Ahmed Mosque. The patriarchate moved to the Church of the Holy Apostles, which became the city's cathedral. The complex remained a mosque until 1931, when it was closed to the public for four years. It was re-opened in 1935 as a museum under the secular Republic of Turkey, and the building was Turkey's most visited tourist attraction as of 2019.
In 2020, the Council of State annulled the 1934 decision to establish the museum, and the Hagia Sophia was reclassified as a mosque. The decision was highly controversial, sparking divided opinions and drawing condemnation from the Turkish opposition, UNESCO, the World Council of Churches and the International Association of Byzantine Studies, as well as numerous international leaders, while several Muslim leaders in Turkey and other countries welcomed its conversion.
References:Rosenborg Palace was built in the period 1606-34 as Christian IV’s summerhouse just outside the ramparts of Copenhagen. Christian IV was very fond of the palace and often stayed at the castle when he resided in Copenhagen, and it was here that he died in 1648. After his death, the palace passed to his son King Frederik III, who together with his queen, Sophie Amalie, carried out several types of modernisation.
The last king who used the place as a residence was Frederik IV, and around 1720, Rosenborg was abandoned in favor of Frederiksborg Palace.Through the 1700s, considerable art treasures were collected at Rosenborg Castle, among other things items from the estates of deceased royalty and from Christiansborg after the fire there in 1794.
Soon the idea of a museum arose, and that was realised in 1833, which is The Royal Danish Collection’s official year of establishment.