Budapest is the capital and the largest city of Hungary, the largest in East-Central Europe and the seventh largest in the European Union. It is the country's principal political, cultural, commercial,industrial, and transportation centre, sometimes described as the primate city of Hungary. According to 2011 Census, Budapest had 1.74 million inhabitants, down from its 1989 peak of 2.1 million due to suburbanization. The Budapest Commuter Area is home to 3.3 million people. The city covers an area of 525 square kilometres (202.7 sq mi) within the city limits. Budapest became a single city occupying both banks of the river Danube with a unification on 17 November 1873 of west-bank Buda and Óbuda with east-bank Pest.
The history of Budapest began with Aquincum, originally a Celtic settlement that became the Roman capital of Lower Pannonia. Hungarians arrived in the territory in the 9th century. Their first settlement was pillaged by the Mongols in 1241-42.The re-established town became one of the centres of Renaissance humanistculture in the 15th century.