Martinus
Emperor
Last night, I built the Lourve, this requires 2 artifacts and 2 great works of art all from different civs and different eras. I had a Shoshone industrial era painting, and a Moroccan ancient artifact. plus some more of my Shoshone art and Shoshone artifacts. So, since I was the first to get dig sites, no one else could trade with me for artifacts (you can only swap of the same kind, and you cant swap music)........I traded my art stuff for other civ's art from different eras and put my own artifact in there as well............I ended up with a Polish renaissance art, and Portugese medieval art, a classical Shoshone artifact, and an ancient Moroccan artifact, and it added +6 tourism theming bonus (now had I been France, that bonus would have been doubled to +12
That is in addition to the set amount of +2 per Great Work/Artifact, so the Lourve itself was generating +14tourism alone! (if it were france it would have been +20!)
It's pretty fun going in and trying to move all the pieces around to generate the most tourism you can!
EDIT: time to correct myself. The theming bonus for the Lourve is +8, so that's +16 tourism for non-French civs and +24 for France! The Lourve is a BIG deal when it comes to tourism and the new cultural victory!
Don't forget that completing Aesthetics further doubles the theming bonuses (but I am not sure if for France this means you would have 48 or just 36). And then you have the Internet.