Located at the center of the Paris-Brussels-London triangle, Lille is at a major crossroads of the french high-speed train network, with many trains a day transporting travellers at 300 km/h from and to Brussels in 40 minutes, Paris in one hour, and London in one hour and 20 minutes.
There is a small airport near Lille (Lille-Lesquin, LIL), which is served by several airlines, in particular low-cost ones, with fligths mainly from the south of Europe.
For most international travellers, it is more convenient to land at Paris-Charles de Gaulle airport (CDG), and then to take the high-speed train at the airport TGV train station (located in terminal 2) to arrive in Lille just 50 minutes later. Those travelling with Air France should take note that it is possible to have the train ticket from CDG to Lille included in the plane ticket. For this, choose XDB (International Lille-Europe train station, considered as a proximity "airport") as the final destination airport code. The plane+train ticket is quite often cheaper than the ticket to CDG, due to some obscure ticketing logic.
From Brussels-Zaventem international airport, there is a 20-minute train travel to Brussels ("Bruxelles Midi" train station) and then it will take less than 40 minutes to reach Lille with high-speed trains (including "Eurostar" trains heading for London)
For cost-conscious attendees, there is still another alternative, which is to land at the smaller Brussels-South Charleroi Airport, a destination for several low-cost airlines, most notably Ryan Air. From the airport, it will take you 90 minutes to reach Lille with the Lille shuttle (direct coach line).