London is the capital of England and the United Kingdom. It was founded in 43 A.D. by the Romans as a town called Londinium. The Romans had built the city near an important river and a sea port where they built buildings, roads and bridges. It is the largest city in the United Kingdom and the European Union with a population of over 8 million people. London is a major financial center and a tourist destination with many famous landmarks, such as Buckingham Palace, Big Ben, Tower Bridge and St. Paul's Cathedral to name but a few.
London was the largest city in England until it began to lose its position in the early 19th century. Other cities grew larger, including Manchester, Birmingham and Liverpool. Today, London is the second-largest city in England after Birmingham.
The city is a major international transport hub. It has the most extensive rail network in the UK, including the world-famous London Underground, known as the Tube. The city's largest airport is Heathrow, which has flights to many parts of Europe and worldwide. It is the busiest airport in Europe by passenger traffic and the second-busiest airport in the world after Hartsfield–Jackson Atlanta International Airport.