Bilbao is a municipality and city in Spain, a major city in the province of Biscay in the autonomous community of the Basque Country. It is the main urban area in what is defined as the Greater Basque region. Situated in the north-central part of Spain, its main urban core is surrounded by two small mountain ranges. After its foundation in the early 14th century by Diego López V de Haro, head of the powerful Haro family, the city was a commercial hub of the Basque Country that enjoyed significant importance in Green Spain. This was due to its port activity based on the export of iron extracted from the Biscayan quarries. Throughout the nineteenth century and the beginning of the twentieth, Bilbao experienced heavy industrialisation, making it the centre of the second-most industrialised region of Spain. Today, Bilbao is a vigorous service city that is experiencing an ongoing social, economic, and aesthetic revitalisation process, started by the iconic Bilbao Guggenheim Museum, and continued by infrastructure investments, such as the airport terminal, the rapid transit system, the tram line, the Alhóndiga, and the currently under development Abandoibarra and Zorrozaurre renewal projects. Bilbao is also home to football club Athletic Club de Bilbao, a significant symbol for Basque nationalism due to its promotion of Basque players and one of the most successful clubs in Spanish football history.

Dublin is the largest and capital city of Ireland. The English name is derived from the Irish name Dubh Linn, meaning "black pool". It is a primate city with an urban population of over 1 million, containing almost 25% of the country's population. Dublin is situated near the midpoint of Ireland's east coast, at the mouth of the River Liffey, and at the centre of the Dublin Region. The city is listed by the Globalization and World Cities Research Network (GaWC) as a global city, with a ranking of "Alpha-", placing it among the top thirty cities in the world. It is a historical and contemporary centre for education, the arts, administration, economy and industry.

The capital of Portugal, Lisbon (Portuguese: Lisboa) has experienced a renaissance in recent years, with a contemporary culture that is alive and thriving and making its mark in today's Europe. Perched on the edge of the Atlantic Ocean, Lisbon is one of the rare Western European cities that faces the ocean and uses water as an element that defines the city. Lisbon enchants travellers with its white-bleached limestone buildings, intimate alleyways, and an easy-going charm that makes it a popular year-round destination.

Bordeaux is a port city on the Garonne River in southwest France, with an estimated (2008) population of 250,082. The Bordeaux-Arcachon-Libourne metropolitan area, has a population of 1,010,000 and constitutes the sixth-largest urban area in France. It is the capital of the Aquitaine region, as well as the prefecture of the Gironde department. Its inhabitants are called Bordelais. Bordeaux is the world's major wine industry capital. It is home to the world's main wine fair, Vinexpo, while the wine economy in the metro area moves 14.5 billion euros each year. Bordeaux wine has been produced in the region since the eighth century. The historic part of the city is on the UNESCO World Heritage List as "an outstanding urban and architectural ensemble" of the 18th century.

Porto (also known as Oporto in English), is the second largest city in Portugal after Lisbon and one of the major urban areas of the Iberian Peninsula. The urban area of Porto, which extends beyond the administrative limits of the city, has a population of 1.4 million (2011) in an area of 389 km2 (150 sq mi), making it the second-largest urban area in Portugal. Located along the Douro river estuary in Northern Portugal, Porto is one of the oldest European centres, and its historical core was proclaimed a World Heritage Site by UNESCO in 1996. The western part of its urban area extends to the coastline of the Atlantic Ocean. Its settlement dates back many centuries, when it was an outpost of the Roman Empire. One of Portugal's internationally famous exports, port wine, is named for Porto, since the metropolitan area, and in particular the caves of Vila Nova de Gaia, were responsible for the packaging, transport and export of the fortified wine. In 2014, Porto was elected The Best European Destination by the Best European Destinations Agency.