Question: Palácio de Ferro is located in the capital city with a population over what figure?
Context: The Mateus Palace (Portuguese: Palácio de Mateus , Solar de Mateus or Casa de Mateus) is a palace located in the civil parish of Mateus, municipality of Vila Real, Portugal.  Architect Nicolau Nasoni was involved in the project for the construction of the palace, which took place in the 18th century. Verride Palace, or the Palace of Santa Catarina, (Portuguese: Palácio de Verride; Palácio de Santa Catarina) is an 18th-century Portuguese palace located in Lisbon, Portugal. The Moçâmedes Railway (Portuguese: "Caminho de Ferro de Moçâmedes (CFM)" ) is a 860 km railway line in Angola, between Namibe and Menongue.  The line is operated by the company Caminhos de Ferro de Moçâmedes E.P.  The port city of Moçâmedes was renamed Namibe in 1985, so the railway is sometimes called the "Namibe Railway" (Portuguese: "Caminho de Ferro do Namibe" ), However, the railway company retained its original legal name. Paço de São Cristóvão (] , English: Saint Christopher's Palace ; also known as Palácio Imperial or Palácio de São Cristóvão) is a palace located in the Quinta da Boa Vista park in Rio de Janeiro, Brazil.  It is the former residence of the Emperors of Brazil.  It currently houses the National Museum of Brazil. The Royal Palace of Évora (Portuguese: "Paço Real de Évora"), also known as the Royal Palace of São Francisco ("Paço Real de São Francisco") and the Palace of King Manuel I ("Palácio de D. Manuel"), is a former royal residence of the Kings of Portugal, in Évora, capital of the Alentejo. Luanda, formerly named São Paulo da Assunção de Loanda, is the capital and largest city in Angola, and the country's most populous and important city, primary port and major industrial, cultural and urban centre.  Located on Angola's coast with the Atlantic Ocean, Luanda is both Angola's chief seaport and its administrative centre.  It has a metropolitan population of over 6 million.  It is also the capital city of Luanda Province, and the world's fourth most populous Portuguese-speaking city, behind only São Paulo, Rio de Janeiro, and Salvador, Bahia all in Brazil, and the most populous Portuguese-speaking capital city in the world, ahead of Brasília, Maputo and Lisbon. Huambo, formerly Nova Lisboa (English: "New Lisbon", 1928–1975), is the capital of the province of Huambo in Angola.  The city is located about 220 km E from Benguela and 600 km SE from Luanda.  The city is the second largest in Angola, after the capital city, Luanda.  Huambo is a main hub on the "Caminho de Ferro de Benguela (CFB)" (the Benguela Railway), which runs from the port of Lobito to the Democratic Republic of the Congo's southernmost province, Katanga.  Huambo is served by the Albano Machado Airport (formerly Nova Lisboa Airport). Palácio de Ferro (English: Iron Palace ) is a historical building in the Angolan capital Luanda, "believed to be designed and built by – or by someone associated with – Gustave Eiffel", builder of the world-famous icons, the Eiffel Tower in Paris and the Statue of Liberty in New York City. Founded in 1983 by the brothers Luiz F. Machado and João H. Machado, the band had several line-ups through its history.  It all started with the name, chosen by João Machado who, after a research on the Middle Ages, had a special interest in the Crusades, in the Knights Templar and in the Inquisition.  The period which Silvio Mazzei and Roberto Moura (drums, former Dorsal Atlântica) joined the band marked the phase when Inquisição started to play very often in Rio de Janeiro, especially at Circo Voador and Caverna 2, the city's main Heavy Metal venues.  They also recorded another demo with this line-up, with the songs Cruz de Ferro and Cães Malditos, at Estúdio Performance, which belonged to Daniel Cheese, producer and former guitarist of the band Água Brava.  In 1987, the band recorded their third demo tape, again at Estúdio Performance, including the songs Tempo Fechado, Cruz de Ferro, Cães Malditos, Insano and Napalm.  This tape had a great response, and was sold in the most important underground record stores in Brazil at the time. The Palacette of Belomonte (Portuguese: "Palacete de Belomonte/Palácio de Belomonte/Casa dos Pacheco Pereira" ) is a former-residence on "Rua de Belomonte", in the civil parish of Cedofeita, Santo Ildefonso, Sé, Miragaia, São Nicolau e Vitória, in the northern Portuguese city of Porto.
Answer: 6 million