The world grows ever smaller. You could log on, book a flight, and hop an airplane across the world within hours if you live anywhere near these major international hubs for air travel.

5. Toronto Pearson International Airport (YYZ)

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In fifth place, Toronto Pearson International Airport in Canada is one of the most connected airports in the world. The Air Canada hub is Canada’s busiest metropolitan center and also the country’s busiest airport. In addition to its plentiful international connections, Toronto Pearson also offers non-stop domestic flights to all major Canadian cities. It takes its name from Lester B. Pearson, the Nobel Peace Prize-winning Prime Minister of Canada.

4. Amsterdam Airport Schiphol (AMS)

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AMS of the Netherlands is the fourth most connected airport in the world and the third busiest in Europe. The airport serves 104 different airlines, and in 2016 it was awarded a royal seal from King Willem Alexander of the Netherlands. The origins of its name are cryptic with one of the most popular folk tales being that the nearby lake was the site of several shipwrecks, earning it the title of ship grave, or “schip” “hol.” Its design is based on a single-terminal concept with one large terminal split into three departure halls.

3. Frankfurt Airport (FRA)

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Nearly tied with O’Hare, Frankfurt Airport in Germany is the third most internationally connected airport in the world. The Lufthansa main hub boasts twin passenger terminals and four runways with a total capacity estimated at 65 million passengers per year. The airport was strategically developed near the Frankfurter Kreuz Autobahn intersection as it was one of the busiest motorways in Europe at the time of its construction.

Unlike the two airports higher on this list, FRA was initially opened for commercial use in 1936, before the start of World War II and its conversion to a military base. Before its conversion, it had gotten off to rough start, as it once served as the base of the Hindenburg. After restrictions for German air travelers were relived in 1951, the airport began its development into the logistic hub that it is today.

2. O’Hare International Airport (ORD)

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In close second, Chicago’s O’Hare International Airport takes the cake for second-most-connected. Like the number-one entry on this list, the “busiest square mile in the world” started out servicing military transports in World War II before it was converted for civilian use. It takes its name after Medal of Honor recipient Edward “Butch” O’Hare, the Navy’s first flying ace.

Up until 1998, O’Hare was in fact the busiest airport in the world, whereas it now ranks at sixth busiest. Its ambitious beginnings made it home to several innovations in civilian air travel of the time, including direct highway access as well as the use of concourses, jet bridges, and underground refueling systems. In recent times, connecting flights across distant terminals in the expansive airport had become so common as to warrant recent renovations in the transit system with new terminal buses to transport passengers between flights.

1. Heathrow Airport (LHR)

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If you’ve done any extensive amount of international travel, the odds are that you wound up at Heathrow at some point. London’s main international airport has a reputation as the world’s most internationally connected airport. As of 2018, Heathrow offered 66,000 different international connections with no more than a six-hour wait at its busiest travel times. In 2015, Heathrow was the busiest airport in Europe, 14 percent ahead of Paris-Charles de Gaulle Airport and 22 percent Istanbul Ataturk Airport in passenger traffic.

During its early years, Heathrow was a small air field in a rural hamlet. Development in earnest began in 1944 for long-distance military aircraft travel, but the war ended before its construction was completed, and its development was continued instead as a civil airport.

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