It's amazing what exists beneath our feet! Pricing signs advertising the site are a bit out of date (now it's 6eu per adult). Biggest gripe is that the experience benefits enormously from an audio guide but it's far from obvious where to find it (small A4 Red sheet on the wall of the first room before the sliding door) but could do with being posted much more frequently around the site. As for the site itself: a decent introduction exhibit before being let loose into the catacombs yourself. The jewel in the crown is the first and largest accessible catacomb which was genuinely impressive. After this we discovered there is about 22 of these catacombs (all appear to be smaller than the first) but access tends to be quite limited and a few (5 or 6) were entirely closed. Once you cross the road into the second half it is much more peaceful and access to many of the smaller 'family sized' tombs are more the flavour of the tombs. I recall reading there is around 2000m of catacombs in total but I think we really get about a fifth of that either for safety reasons or limited space accessing some portions. Anyway it's really worth seeing and you get a good bit of cardio accessing and leaving the latter tombs. Architecturally considerate planning gives a familiar feeling above the ground which contrasts nicely with the nature of the hollows beneath your feet.