One of our recent adventures was to explore Paris from it's high(est) point - The Eiffel tower, to the lowest possible depths - the tunnels beneath the city. The catacombs.
I wasn't so sure about going up the Eiffel tower. Although it's the absolute icon of the city it seemed such a touristy thing to do. And in August it's not great to be a tourist in Paris - there are just so damn many of them. Even the tourists will tell you that the only thing wrong with Paris is - the tourists! The long queue we had to stand in was enough to swear me off any tourist type activities for about a week following. But the view over the city when we finally reached the top was worth it. The world reduced to ant-like miniatures.
Visiting the catacombs was a crazy experience - after descending a 19 metre stone spiral staircase you find yourself in a dank and musty tunnel. After passing through a few stone walled tunnels and coming across some sculpture you are greeted with the inscription "Arrête, c'est ici l'empire de la Mort" - "Stop, this is the empire of Death''. Delightful. From here on stacks of skulls and bones line the passageways - some in quite decorative formations. It's a bizarre attraction for a city. A bit macabre but still fascinating and I'm sure its curiosity that drives most visits. Certainly true in my case.
The tunnels open to the public represent only a small corner of the underground tunnel system of Paris. There are over 300km of underground passages underneath the city. Some of it is explored nowdays by cataphiles (tunnel enthusiasts) although it's illegal to do so. I've even read of an underground cinema and raves taking place in the tunnels.
Not the kind of place I'd like to party. Actually given the choice of 'high' or 'low' I think I'd select the former!