Heathrow Airport is the busiest of the airports in London, followed by Gatwick Airport. It is additionally the busiest in the world for international passenger traffic. Taking domestic flights into consideration, it is the world's second busiest. The highest number of passengers on flight departures from Heathrow are on their way to New York City, and nearly 13 million passengers travel between Heathrow and the United States each year. Other destinations for flight departures from Heathrow include other UK cities, major cities in Eastern and Western Europe, and cities all over Asia, South America, and Africa.
Like Gatwick, there also is a convenient high-speed train connection. This is the Heathrow Express that travels between the airport and Paddington Station in Central London. Step out of any exit at Paddington Station, and you'll be only four blocks from famous Hyde Park and surrounded by a number of Hyde Park hotels.
The Heathrow Express takes only fifteen minutes to get into the city, with departures between the two leaving every fifteen minutes. All of the four airport terminals enter into the central Heathrow Arrivals area, and that is where the public bus and train transportation options become available.
Heathrow Airport handles a good 20 million passengers more than it was designed to handle, and its location within the greater metropolitan area makes expansion problematic. This has caused a number of problems in recent years, most notably in flight delays. Another issue with the facility is its location, just to the west of the city and the east-west orientation of its two runways. This means that landing patterns are most often directly over the city, causing complaints from residents on the ground and safety concerns. Most other major metropolitan airports are located to the north or south of their respective cities, minimizing this issue. Attractions close to Heathrow include both Windsor Castle and Hampton Court Palace. If you are connecting to another flight and have a layover of a few hours, you can visit both of these important pieces of London history. You can stow your bags at the airport, and take a bus.