RATP, alongside the Mayor of Montrouge, launched the start of civils works on an extension of the Line 4 metro.
The 2.7-kilometre extension will add two new stations, in Montrouge and Bagneux, to what is the second-busiest metro line in the French capital.
Due to open in 2020, the extension will put Bagneux within half an hour of the centre of Paris. The two new stations will welcome more than 37,000 passengers a day.
The €380 million project is being jointly funded by the state, the Ile-de-France Region and the Hauts-de-Seine department.
As well as the southern extension to Bagneux, Line 4 is being upgraded to support driverless operation – a programme that will be completed by 2022. In the future, it will also connect to the new Grand Paris Line 15.