Budapest was created in 1873 by merging Buda, Óbuda and Pest.
The three formerly separate settlements sit along the Danube. Buda and Óbuda are on the river’s western, hilly bank, while Pest occupies the flatter eastern side. The unification created the political and economic centre of the Kingdom of Hungary.
Buda was associated with the royal castle and hills, Óbuda preserved the site of the Roman settlement of Aquincum, and Pest grew into a major commercial district. The Chain Bridge, completed in 1849, helped connect the riverbanks before the formal merger.
Budapest is sometimes described as a single ancient city, but its modern municipal identity dates from the 19th-century union. The Danube remains central to the capital’s geography, with landmarks such as the Hungarian Parliament Building and Buda Castle facing the river.