While fully mapped, this sage advice from The Independent about a decade go is probably still relevant:

It is advisable to never trust anyone, any signage or any online maps…

( Going underground: Exploring the Paris Catacombs )

However, that may no longer be the case.

The labyrinthine excavations under Rome, and the hidden passages, paths, rooms and chambers of Venice, Florence and Naples were 3D mapped to create interactive virtual-reality models for TV programmes fronted by Alexander Armstrong

So if anyone wants to do likewise in - or under - Paris, the technology is already available, if not actually in place (minus creative signage, dodgy guides, or maps that may or may not be economical with the actualité), so perhaps a quick call to the BBC (or ScanLAB Projects) might be in order.

See

BBC One - Italy's Invisible Cities, Series 1

Alexander Armstrong and Dr Michael Scott uncover the hidden history of Italian city life. ... Explore stunning 360º videos of Naples, Florence and Venice ...