OK, that was a little exaggerated, but only slightly!
“The Cité's first stones were placed in 122 BC by the world's greatest conquerors at the time, the Romans. They occupied the Languedoc until 5th century, until the arrival of the Visigoths.”
So the first stone of Carcassonne City was laid by the Romans about 2023 + 122, 2145 years ago, not 2500!