The project consists of new rapid transit lines and the extension of existing lines being built in the Île-de-France region of France. The project comprises four new lines for the Paris Métro, plus extensions of the existing Lines 11 and 14.
This will cover a total of 200 kilometres (120 mi) of new tracks and 68 new stations are to be added, serving a projected 2 million passengers a day.
We explore what it takes to build a mega project like this under one of Europe’s biggest cities:
