Budapest later, with the help of the Russian Empire. 1867 was the year of Reconciliation that brought about the birth of Austria-Hungary. This made Budapest the twin capital of a dual monarchy. It was this compromise which opened the second great phase of development in the history of Budapest, lasting until World War I. In 1849 the Chain Bridge linking Buda with Pest was opened as the first permanent bridge across the Danube and in 1873 Buda and Pest were officially merged with the third part, Óbuda (Old Buda), thus creating the new metropolis of Budapest. The dynamic Pest grew into
Budapest there are forty theatres, seven concert halls and an opera house. Outdoor festivals, concerts and lectures enrich the cultural offer of summer, which are often held in historical buildings. The largest theatre facilities are the Budapest Operetta and Musical Theatre, the József Attila Theatre, the Katona József Theatre, the Madách Theatre, the Hungarian State Opera House, the National Theatre, the Vigadó Concert Hall, Radnóti Miklós Theatre, the Comedy Theatre and the Palace of Arts, known as "MUPA". The Budapest Opera Ball is an annual Hungarian society event taking place in the building of the Budapest Opera ("Operaház") on the last