France, June 16 -- To house the thousands of soldiers tasked with keeping the Paris Olympics safe, France is building the largest army camp its mainland has seen since World War II, at breakneck pace.

Row upon row of temporary barracks have risen up where a fairground in eastern Paris once stood, green army bunk beds and massive mess halls for 4,500 troops replacing merry-go-rounds and candyfloss.

Construction of the camp is being held to a record deadline of 65 days, with the first soldiers due to arrive July 3.

Thirteen days later, they will be guarding the showpiece opening ceremony of the 2024 Olympics along a six-kilometre stretch of the River Seine- the focus of persistent security worries.

"We're on schedule," insisted Denis Le...