Thalys is a high-speed train network built around a dedicated track between Paris and Brussels. This track is actually shared with Eurostar trains that go from Paris or Brussels to London through Lille and the Channel tunnel. The trains are TGVs (train à grande vitesse), with modification to run on several different types of power supply.
Beyond Brussels, the main cities Thalys trains reach are Antwerp, The Hague, Rotterdam, Amsterdam, Liège and Cologne, partly on dedicated high-speed tracks (some of these are yet to be built), partly on older tracks shared with normal-speed trains.
Near or beyond Paris the French high-speed network opens the way for high-speed links from or through Brussels to other French cities like Avignon and Marseille, Geneva in Switzerland, and locations like Paris' main international airport (Roissy - Charles de Gaulle) and the Disneyland leisure park in Marne-la-Vallée.
The link with Roissy-Charles-de-Gaulle airport allowed Air France to cancel its aerial line between Paris and Brussels; instead, Air France books seats on Thalys trains.
Travel time from Brussels (Gare du Midi/Zuidstation) to Paris (Gare du Nord) is normally 1 hour 25, for a distance of approximatively 300 km.
http://www.thalys.com -- Thalys official site
