The bridge over the River Tarn in the Massif Central mountains will carry vehicles across a 2.5km (1.5 miles) valley at a height of 270m (885ft).
When finished, the highest pillar will stand at just over 340m (1,115ft) tall. Once its pylons and giant suspension cables are in place, the structure will be higher than the Eiffel Tower, which reaches 343m.
It is being constructed by Eiffage, the company that built the Eiffel Tower, and will have taken three-and-a-half years to complete.
The company has shouldered the 260m euro construction cost ($300m) in return for the right to collect receipts from a bridge toll for 75 years.
Like Concorde and the Channel Tunnel, the bridge is Franco-British. The world-renowned architect Norman Foster is behind the design.
The project was due to take three years, but weather conditions put work on the bridge behind schedule.