The Histoire de Paris - rough translation:
The ramparts built at the beginning of 13th century were never useful militarily until the time of Charles V:
on the Left Bank, they are considered still sufficient in the 14th century, and simply consolidated then surrounded by a dry ditch.
The street Mazarine testifies some: this old way outside of the enclosure of Philippe-Auguste is indeed baptized
in the 17th century "rue des Fossés de Nesle” (street of the Ditches of Nesle).

As the capital grew, the medieval fortifications were slowly absorbed into the urban fabric - the wall became the border of property,
a base of a house or a stone quarry, and its turns are used by homes, workshops, or even as vaults.

Here, a long section of wall and the base of a tower are visible inside the underground car park.
These successive re-employments safeguarded multiple fragments of the monumental enclosure, thus preserving it radical demolition.

http://www.philippe-auguste.com/uk/