Barcelona is a city in Spain. It is the capital and largest city of Catalonia, as well as the second most populous municipality of Spain. With a population of 1.6 million within city limits, its urban area extends to numerous neighbouring municipalities within the Province of Barcelona and is home to around 4.8 million people, making it the sixth most populous urban area in the European Union after Paris, London, Madrid, the Ruhr area and Milan. It is one of the largest metropolises on the Mediterranean Sea, located on the coast between the mouths of the rivers Llobregat and Besòs, and bounded to the west by the Serra de Collserola mountain range, the tallest peak of which is 512 metres (1,680 feet) high.

Founded as a Roman city, in the Middle Ages Barcelona became the capital of the County of Barcelona. After merging with the Kingdom of Aragon, Barcelona continued to be an important city in the Crown of Aragon as an economic and administrative centre of this Crown and the capital of the Principality of Catalonia. Barcelona has a rich cultural heritage and is today an important cultural centre and a major tourist destination. Particularly renowned are the architectural works of Antoni Gaudí and Lluís Domènech i Montaner, which have been designated UNESCO World Heritage Sites. The headquarters of the Union for the Mediterranean are located in Barcelona. The city is known for hosting the 1992 Summer Olympics as well as world-class conferences and expositions and also many international sport tournaments.

Barcelona is one of the world's leading tourist, economic, trade fair and cultural centres, and its influence in commerce, education, entertainment, media, fashion, science, and the arts all contribute to its status as one of the world's major global cities. It is a major cultural and economic centre in southwestern Europe, 24th in the world (before Zürich, after Frankfurt) and a financial centre. In 2008 it was the fourth most economically powerful city by GDP in the European Union and 35th in the world with GDP amounting to €177 billion. In 2012 Barcelona had a GDP of $170 billion; and it was leading Spain in employment rate in that moment.

In 2009 the city was ranked Europe's third and one of the world's most successful as a city brand. In the same year the city was ranked Europe's fourth best city for business and fastest improving European city, with growth improved by 17% per year, and the city has been experiencing strong and renewed growth for the past three years. Since 2011 Barcelona has been a leading smart city in Europe. Barcelona is a transport hub, with the Port of Barcelona being one of Europe's principal seaports and busiest European passenger port, an international airport, Barcelona–El Prat Airport, which handles over 50 million passengers per year, an extensive motorway network, and a high-speed rail line with a link to France and the rest of Europe.

The city of Cartagena, known in the colonial era as Cartagena de Indias, is a major port founded in 1533, located on the northern coast of Colombia in the Caribbean Coast Region. It was strategically located between the Magdalena and Sinú rivers and became the main port for trade between Spain and its overseas empire, establishing its importance by the early 1540s. During the colonial era it was a key port for the export of Peruvian silver to Spain and for the import of enslaved Africans under the asiento system. It was defensible against pirate attacks in the Caribbean. It is the capital of the Bolívar Department, and had a population 971,592 as of 2016. It is the fifth-largest city in Colombia and the second largest in the region, after Barranquilla. The urban area of Cartagena is also the fifth-largest urban area in the country. Economic activities include the maritime and petrochemicals industries, as well as tourism.

The city was founded on June 1, 1533, and named after Cartagena, Spain, settlement in the region around Cartagena Bay by various indigenous people dates back to 4000 BC. During the Spanish colonial period Cartagena served a key role in administration and expansion of the Spanish empire. It was a center of political, ecclesiastical, and economic activity. In 1984, Cartagena's colonial walled city and fortress were designated a UNESCO World Heritage Site.

Málaga is a municipality, capital of the Province of Málaga, in the Autonomous Community of Andalusia, Spain. With a population of 569,130 in 2015, it is the second-most populous city of Andalusia and the sixth-largest in Spain. The southernmost large city in Europe, it lies on the Costa del Sol (Coast of the Sun) of the Mediterranean, about 100 kilometres (62.14 miles) east of the Strait of Gibraltar and about 130 km (80.78 mi) north of Africa.

Málaga's history spans about 2,800 years, making it one of the oldest cities in the world. According to most scholars, it was founded about 770 BC by the Phoenicians as Malaka From the 6th century BC the city was under the hegemony of Ancient Carthage, and from 218 BC, it was ruled by the Roman Republic and then empire as Malaca (Latin). After the fall of the empire and the end of Visigothic rule, it was under Islamic rule as Mālaqah for 800 years, but in 1487, the Crown of Castille gained control after the Reconquista. The archaeological remains and monuments from the Phoenician, Roman, Arabic and Christian eras make the historic center of the city an "open museum", displaying its history of nearly 3,000 years.

This important cultural infrastructure and the artistic heritage have culminated in the nomination of Málaga as a candidate for the 2016 European Capital of Culture.

The painter and sculptor Pablo Picasso, Hebrew poet and Jewish philosopher Solomon Ibn Gabirol and the actor Antonio Banderas were born in Málaga. The magnum opus of Cuban composer Ernesto Lecuona, "Malagueña", is named after the music of this region of Spain.

The most important business sectors in Málaga are tourism, construction and technology services, but other sectors such as transportation and logistics are beginning to expand. The Andalusia Technology Park (PTA), located in Málaga, has enjoyed significant growth since its inauguration in 1992. Málaga is the main economic and financial centre of southern Spain, home of the region's largest bank, Unicaja, and the fourth-ranking city in economic activity in Spain behind Madrid, Barcelona and Valencia.

Lisbon is the capital and the largest city of Portugal, with an estimated population of 505,526 within its administrative limits in an area of 100.05 km2. Its urban area extends beyond the city's administrative limits with a population of around 2.8 million people, being the 11th-most populous urban area in the European Union. About 3 million people live in the Lisbon Metropolitan Area (which represents approximately 27% of the country's population). It is mainland Europe's westernmost capital city and the only one along the Atlantic coast. Lisbon lies in the western Iberian Peninsula on the Atlantic Ocean and the River Tagus. The westernmost areas of its metro area form the westernmost point of Continental Europe, which is known as Cabo da Roca, located in the Sintra Mountains.