With 75 km of track, it will be the longest metro line in France! Anticipated by many residents of the Paris region, line 15 will run all around Paris, crossing no less than 45 communes. While the opening of the southern section was announced for the end of 2025, its commissioning has now been postponed until summer 2026. The inauguration of the Eastern and Western sections is scheduled for 2031. Here's everything you need to know about the future Grand Paris Express metro line, which will carry over 1.5 million passengers every day.