Rio de Janeiro is the second-most populous municipality in Brazil and the sixth-most populous in the Americas. The metropolis is anchor to the Rio de Janeiro metropolitan area, the second-most populous metropolitan area in Brazil and sixth-most populous in the Americas. Rio de Janeiro is the capital of the state of Rio de Janeiro, Brazil's third-most populous state. Part of the city has been designated as a World Heritage Site, named "Rio de Janeiro: CariocaLandscapes between the Mountain and the Sea", by UNESCO 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. Later, in 1763, it became the capital of the State of Brazil, a state of the Portuguese Empire. In 1808, when the Portuguese Royal Court transferred itself from Portugal to Brazil, Rio de Janeiro became the chosen seat of the court of Queen Maria I of Portugal, who subsequently, in 1815, under the leadership of her son, the Prince Regent, and future King João VI of Portugal, raised Brazil to the dignity of a kingdom, within the United Kingdom of Portugal, Brazil, and Algarves. Rio stayed 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 colonising 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 Brasília.

Tarragona is a port city located in northeast Spain on the Costa Daurada by the Mediterranean Sea. Founded before the 5th century BC, it is the capital of the Province of Tarragona, and part of Tarragonès and Catalonia. Geographically, it is bordered on the north by the Province of Barcelona and the Province of Lleida. The city has a population of 201,199 (2014).

Marseille is the second-largest city of France. The main city of the historical province of Provence, it nowadays is the prefecture of the department of Bouches-du-Rhône and region of Provence-Alpes-Côte d'Azur. It is located on France's south coast near the mouth of the Rhône river. The city covers an area of 241 km2 (93 sq mi) and had a population of 852,516 in 2012. Its metropolitan area, which extends over 3,173 km2 (1,225 sq mi) is the third-largest in France after Paris and Lyon, with a population of 1,831,500 as of 2010.

 Known to the ancient Greeks and Romans as Massalia, Marseille was an important European trading centre and remains the main commercial port of the French Republic. Marseille is now France's largest city on the Mediterranean coast and the largest port for commerce, freight and cruise ships. The city was European Capital of Culture in 2013 and European Capital of Sport in 2017; it hosted matches at the 1998 World Cup and Euro 2016. It is home to Aix-Marseille University.

Genoa is the capital of the Italian region of Liguria and the sixth-largest city in Italy. In 2015, 594,733 people lived within the city's administrative limits. As of the 2011 Italian census, the Province of Genoa, which in 2015 became the Metropolitan City of Genoa, counted 855,834 resident persons. Over 1.5 million people live in the wider metropolitan area stretching along the Italian Riviera.

 Located on the Gulf of Genoa in the Ligurian Sea, Genoa has historically been one of the most important ports on the Mediterranean: it is currently the busiest in Italy and in the Mediterranean Sea and twelfth-busiest in the European Union. Genoa has been nicknamed la Superba ("the proud one") due to its glorious past and impressive landmarks. Part of the old town of Genoa was inscribed on the World Heritage List (UNESCO) in 2006 as Genoa: Le Strade Nuove and the system of the Palazzi dei Rolli. The city's rich cultural history in art, music and cuisine allowed it to become the 2004 European Capital of Culture. It is the birthplace of Christopher Columbus, Andrea Doria, Niccolò Paganini, Giuseppe Mazzini, Renzo Piano and Grimaldo Canella, founder of the House of Grimaldi, among others.

Genoa, which forms the southern corner of the Milan-Turin-Genoa industrial triangle of Northwest Italy, is one of the country's major economic centers. The city has hosted massive shipyards and steelworks since the 19th century, and its solid financial sector dates back to the Middle Ages. The Bank of Saint George, founded in 1407, is among the oldest in the world and has played an important role in the city's prosperity since the middle of the 15th century. Today a number of leading Italian companies are based in the city, including Fincantieri, Selex ES, Ansaldo Energia, Ansaldo STS, Edoardo Raffinerie Garrone, Piaggio Aerospace, Mediterranean Shipping Company and Costa Cruises.