The two spots were both created by Abbott Mead Vickers BBDO and are the first TV work since the Omnicom agency won the pan-European account in 2012.
Both ads are in the same format and use similar scripts but each will feature images of either London or Paris, with English or French voiceovers, depending on the market.
Simon Ratigan directed the spots through the production company HLA, which sent photographers and cameramen onto the streets of each city to capture "real life" footage as well as images of people and interesting locations.
Both ads close with the line "stories are waiting" and ask views to travel by Eurostar to create their own memories. The copywriter was Alex Grieve and the art director was Adrian Rossi.
Lionel Benbassat, the director of marketing for Eurostar, told Campaign: "This approach is quite new: they are mirror films with the same idea and structure but with different moods because they are talking about two different cities.
"We have run the same advertising in three markets before, such as for the Olympics campaign at the in the end of 2011 and beginning of 2012. But for that we had one single ad, which was always shown in English.
"This campaign is much more integrated and will live on various media."
A 30-second and 60-second version of the UK ad will run for six weeks from Sunday (20 October) across national TV. The campaign will be promoted through Eurostar’s platforms such as social media, customer emails and the customer magazine Metropolitan.
Arena was responsible for the media planning. The Havas Media Group agency arranged interactive ads on video-on-demand platforms and bloggers who will blog about their Paris experiences.
Eurostar will also ask passengers to share stories and pictures from Paris and London on social media with the hashtag #wheninparis or #wheninlondon for the chance to feature within a re-edit of the ads, due to go live in December.