Rio de Janeiro (; Portuguese: [iw d(i) ne(j)u] (listen)), or simply Rio, literally River of January, is the second-most populous city in Brazil and the sixth-most populous in the Americas. Rio de Janeiro is the capital of the state of the same name, Brazil's third-most populous state, after So Paulo and Minas Gerais. Part of the city has been designated as a World Heritage Site, named "Rio de Janeiro: Carioca Landscapes between the Mountain and the Sea", on 1 July 2012 as a Cultural Landscape.Founded in 1565 by the Portuguese, the city was initially the seat of the Captaincy of Rio de Janeiro, a domain of the Portuguese Empire. In 1763, it became the capital of the State of Brazil, a state of the Portuguese Empire. In 1808, when the Portuguese Royal Court moved to Brazil, Rio de Janeiro became the seat of the court of Queen Maria I of Portugal. She subsequently, under the leadership of her son the prince regent Joo VI of Portugal, raised Brazil to the dignity of a kingdom, within the United Kingdom of Portugal, Brazil, and Algarves. Rio remained as the capital of the pluricontinental Lusitanian monarchy until 1822, when the War of Brazilian Independence began. This is one of the few instances in history that the capital of a colonizing country officially shifted to a city in one of its colonies. Rio de Janeiro subsequently served as the capital of the independent monarchy, the Empire of Brazil, until 1889, and then the capital of a republican Brazil until 1960 when the capital was transferred to Braslia.

Rio de Janeiro has the second-largest municipal GDP in the country, and 30th-largest in the world in 2008. This is estimated at about R$343 billion (nearly US$201 billion). It is headquarters to Brazilian oil, mining, and telecommunications companies, including two of the country's major corporations, Petrobras and Vale, and Latin America's largest telemedia conglomerate, Grupo Globo. The home of many universities and institutes, it is the second-largest center of research and development in Brazil, accounting for 17 percent of national scientific output according to 2005 data. Despite the high perception of crime, the city actually has a lower incidence of crime than most state capitals in Brazil.Rio de Janeiro is one of the most visited cities in the Southern Hemisphere and is known for its natural settings, Carnival, samba, bossa nova, and balneario beaches such as Barra da Tijuca, Copacabana, Ipanema, and Leblon. In addition to the beaches, some of the most famous landmarks include the giant statue of Christ the Redeemer atop Corcovado mountain, named one of the New Seven Wonders of the World; Sugarloaf Mountain with its cable car; the Sambdromo (Sambadrome), a permanent grandstand-lined parade avenue which is used during Carnival; and Maracan Stadium, one of the world's largest football stadiums. Rio de Janeiro was the host of the 2016 Summer Olympics and the 2016 Summer Paralympics, making the city the first South American and Portuguese-speaking city to ever host the events, and the third time the Olympics were held in a Southern Hemisphere city. The Maracan Stadium held the finals of the 1950 and 2014 FIFA World Cups, the 2013 FIFA Confederations Cup, and the XV Pan American Games.

Brasília (; Portuguese: [bɾaˈziljɐ]) is the federal capital of Brazil and seat of government of the Federal District. The city is located at the top of the Brazilian highlands in the country's Central-West region. It was founded by President Juscelino Kubitschek on 21 April 1960, to serve as the new national capital. Brasília is estimated to be Brazil's third-most populous city. Among major Latin American cities, it has the highest GDP per capita.Brasília was a planned city developed by Lúcio Costa, Oscar Niemeyer and Joaquim Cardozo in 1956 in a scheme to move the capital from Rio de Janeiro to a more central location. The landscape architect was Roberto Burle Marx. The city's design divides it into numbered blocks as well as sectors for specified activities, such as the Hotel Sector, the Banking Sector, and the Embassy Sector. Brasília was inscribed as a UNESCO World Heritage Site in 1987 due to its modernist architecture and uniquely artistic urban planning. It was named "City of Design" by UNESCO in October 2017 and has been part of the Creative Cities Network since then.All three branches of Brazil's federal government are centered in the city: executive, legislative and judiciary. Brasília also hosts 124 foreign embassies. The city's international airport connects it to all other major Brazilian cities and some international destinations, and it is the third-busiest airport in Brazil. It was one of the main host cities of the 2014 FIFA World Cup and hosted some of the football matches during the 2016 Summer Olympics; it also hosted the 2013 FIFA Confederations Cup.

The city has a unique status in Brazil, as it is an administrative division rather than a legal municipality like other cities in Brazil. Although Brasília is used as a synonym for the Federal District through synecdoche, the Federal District is composed of 31 administrative regions, only one of which is the area of the originally planned city, also called Plano Piloto. The rest of the Federal District is considered by IBGE to make up Brasília's metro area.