A Byzantine revival style of architecture occurred in the 19th and 20th centuries. An early example of the revival style in Russia was the Cathedral of Christ the Saviour (1839–84), which was approved by the Tsar to be a model for other churches in the empire. The style's popularity spread through scholarly publications produced after the independence of Greece and the Balkans from the Ottoman Empire. It was used throughout Europe and North America, peaking in popularity between 1890 and 1914. The Greek Orthodox St Sophia's Cathedral (1877–79) and Roman Catholic Westminster Cathedral (begun 1895), both in London, are examples. The throne room of Neuschwanstein Castle (1885–86) was built by King Ludwig II in Bavaria. In the late 19th century, the Hagia Sophia became a widespread model for Greek Orthodox churches. In southeastern Europe, monumental national cathedrals built in the capital cities of formerly Ottoman areas used Neo-Classical or Neo-Byzantine styles. Sofia's Alexander Nevsky Cathedral and Belgrade's Church of Saint Sava are examples, and used Hagia Sophia as a model due to their large sizes. Synagogues in the United States were built in a variety of styles, as they had been in Europe (and often with a mixture of elements from different styles), but the Byzantine Revival style was the most popular in the 1920s. Domed examples include The Temple of Cleveland (1924), the synagogue of KAM Isaiah Israel (1924) in Chicago, based upon San Vitale in Ravenna and Hagia Sophia in Istanbul, and the synagogue of Congregation Emanu-El (1926) in San Francisco.