Australia will need to build a massive "cathedral" to kick off the biggest defence project in the country's history.
Prime Minister Malcolm Turnbull joined France's Armed Forces Minister Florence Parly at the opening of the Australian Future Submarines design office in Cherbourg, west of Paris, on Sunday.
The office will be known as Hughes House after late Rear Admiral Owen "Oscar" Hughes.
In December last year, Australia and France formally sealed a $50 billion agreement under which French naval contractor Naval Group will build a new fleet of diesel-electric submarines based on its nuclear Barracuda.
Speaking at the Barracuda facility, Naval Group CEO Herve Guillou told Mr Turnbull and guests: "This is a sort of cathedral ... and Australia is now here."
The massive assembly hall, which will be required in Adelaide when work begins on the Australian submarines in 2022, allows for one submarine on the finishing line and another on the assembly line.
A workforce of 2,800 people will be needed in Adelaide.
The Cherbourg design facility will receive its first personnel later this year, who will work with Naval Group on the design of the next generation submarine.
The project has the endorsement of French President Emmanuel Macron, who met with Mr Turnbull on a flight from the Hamburg G20 summit to Paris on Saturday and discussed the project over dinner.
"It is not simply a contract," Mr Macron said.
The decision had national, international and strategic outcomes and provided work for Australian industry.
"As president of the republic, I will do everything to ensure we make the necessary arrangements to meet the requirements of this contract but more broadly, to accompany you in this strategic partnership."
Mr Turnbull said the submarine program was the "largest and most ambitious military project in Australia's history".
Ms Parly said Australia and France were on the same "roadmap" when it came to naval development.
The project has not been without controversy.
In early 2016 DCNS was left reeling after details from more than 22,000 pages o f documents relating to submarines it is building for India were published in The Australian newspaper, leading to concerns about the company's ability to protect sensitive data.
Ms Parly said "sensitivities and safety" of the project would be maximised.