Ghost stations in the Paris Metro

I'm just back and it's colder here than Paris! A highlight of the trip was a morning spent underground in the old Metro stations.
Julian, the Metro Man, a wizard who works for the RATP and has been a Metrophile since he was 8, took several of us down into two of the unused Paris Metro stations. We visited Saint Martin, full of peeling posters and old French ads and Villiers, a loop line that went under Parc Monceau, an underground site for officials during WW2, then a training center and now unused.
This is in French with photos but gives a great overview.

http://membres.lycos.fr/metro/5inat/1fantome/fantome.html

Any one else been down there?