As a Kiwi I have a certain fascination with grand old buildings. I mean, all we have is the Auckland Museum and that was opened in 1929, compare that to the Panthéon in Paris which was finished in 1790 and there is really no comparison.
The Panthéon in Paris was originally intended as a Church to honour St. Genevieve, but these days it is most commonly visited as a mausoleum for heaps of famous French dudes and dudettes.
Unlike some of the other visitors, for me it was just a tourist curiosity for me rather than a pilgrimage to see a hero (Marie Curie, Voltaire and Jean-Jacques Rousseau are all entombed there). I was actually just all about the building and seeing the very French style to some of the sculptures there.
In this type of building in Rome you get sculptures of heros and mythological tales, in England you will get Kings and Queens with the occasional lion or unicorn, but in France? You get some very well dressed gentlemen arguing a philosophical point.
I loved this building and (particularly since it is free with the Paris Museum Pass) I think it is well worth a look.