The Hungarian Parliament Building (Hungarian: Országház [ˈorsaːkhaːz], which translates to "House of the Country" or "House of the Nation"), also known as the Parliament of Budapest after its location, is the seat of the National Assembly of Hungary, a notable landmark of Hungary, and a popular tourist destination in Budapest. It is situated on Kossuth Square in the Pest side of the city, on the eastern bank of the Danube. It was designed by Hungarian architect Imre Steindl in neo-Gothic style and opened in 1902. It has been the largest building in Hungary since its completion.

Budapest was united from three cities in 1873, namely Buda, Óbuda, and Pest. Seven years later the Diet resolved to establish a new, representative parliament building, expressing the sovereignty of the nation. The building was planned to face the Danube River. An international competition was held, and Imre Steindl emerged as the victor; the plans of two other competitors were later also realized in the form of the Ethnographic Museum and the Hungarian Ministry of Agriculture, both facing the Parliament Building.

Construction from the winning plan was started in 1885, and the building was inaugurated on the presumed 1,000th anniversary of the country in 1896. The keys to the building being handed over in 1902, however, It was not fully completed until 1904. The architect of the building first went blind and then later, died before its completion.

About 100,000 people were involved in its construction, during which 40 million bricks, half a million precious stones and 40 kg (88 lb) of gold were used. Since World War II the legislature became unicameral, and today the government uses only a small portion of the building. During the People's Republic of Hungary a red star perched on the top of the dome, but it was removed in 1990 after the fall of communism. Mátyás Szűrös declared the Hungarian Republic from the balcony facing Kossuth Lajos Square on 23 October 1989.