Thalys was a brand name used for high-speed train services between Paris Gare du Nord via Brussels-South to either Amsterdam Centraal or to German cities in the Rhein-Ruhr, including Aachen, Cologne, Düsseldorf, Duisburg, Essen and Dortmund. Since 29 September 2023, the services operate under the Eurostar name; sometimes referred to as Eurostar Red, based on the colour of the trains.

The Gare du Nord, officially Paris Nord, is one of the seven large mainline railway station termini in Paris, France. The station is served by trains that run between the capital and northern France via the Paris–Lille railway, as well as to international destinations in Belgium, Germany, the Netherlands and the United Kingdom. Located in the northern part of Paris near the Gare de l'Est in the 10th arrondissement, the Gare du Nord offers connections with several urban transport lines, including Paris Métro, RER and buses. It is the busiest railway station in Europe by total passenger numbers, and the busiest outside Japan. In 2015, the Gare du Nord saw more than 700,000 passengers per day.