Numerous international airlines fly to Mexico City, including British Airways, KLM, Air Canada and United Airlines.
Benito Juarez Airport is a modern airport with two terminals linked by a monorail that can only be used by passengers with a ticket, boarding pass or eticket reference number. Taxis or buses can otherwise be used to go between the terminals - it is too far to walk. It is recommended that the safest way to go from the airport into Mexico City is via a taxi, which can be booked on arrival. There is also a subway from Terminal 1 and a bus, line 4, which runs from both terminals.
There are also direct buses from the airport to Puebla, Querétaro, Toluca, Cuernavaca Tlaxcala, Pachuca and Cordoba, which run every 30 to 40 minutes until mid/ late evening. There is no need to pre-purchase tickets. Look for the signs saying Transporte Foréano/Terrestre.