London is the capital and largest city of England, the United Kingdom, and the European Union. Standing on the River Thames in southeastern England, at the head of its 50-mile (80 km) estuary leading to the North Sea, London has been a major settlement for two millennia.
Madrid is the capital of Spain and the largest municipality in both the Community of Madrid and Spain as a whole. The city has almost 3.2 million inhabitants and a metropolitan area population of approximately 6.5 million.
Paris is the capital and most populous city of France, with an area of 105 square kilometres (41 square miles) and a population of 2,206,488. Since the 17th century, Paris has been one of Europe's major centres of finance, commerce, fashion, science, and the arts.
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.
Milan is a city in northern Italy, capital of Lombardy, and the second-most populous city in Italy after Rome, with the city proper having a population of 1,372,810 while its metropolitan area has a population of 3,242,820.