Something I like regarding Paris, Prague, Vienna and a few other large European cities is that their central areas have few imposing modernist buildings -- policies are that such structures are relegated to peripheral zones. Your tastes may vary, but I find that modernist building are not very interesting to look at, whereas more traditional architecture often is a visual feast.
The well-kept and well-policed Paris tourist zone extends for a mile or so on either side of the River Seine from near the Eiffel Tower downstream to the vicinity of the Lyon and Austerlitz railroad terminals upstream. The main large modernist structures in that zone are the Tour Montparnasse, Opéra de Paris Bastille and the Centre Pompidou, all a ways away from where four-star tourist attractions are found.
So, "just because," here are some photos I took and didn't even bother to crop or digitally manipulate.
Let's start here on the northern segment of the rue. That's my wife impatiently waiting for me to get moving. First, we'll look at the domed building in the background.
Did I just say "visual feast?" Well, this segment of a larger building offers a feast of details that don't quite reach rococo levels. Check out that golden shield near the bottom of the image.
Now we're heading up the hill towards the Jardin du Luxembourg. I don't have an address for this building with its whiff of Art Deco and Art Nouveau, but it's on the southeast corner of the intersection.
Seen from the Jardin using a telephoto zoom. That interesting dark gray appendage might be a decorative cover for chimneys. In any case, it stands above the rooflines of sourrounding buildings and caught my attention.
The cathedral in Chartres isn't the only large church in France with mis-matched towers. Heading down the hill from the Luxembourg is the Saint-Sulpice, where one tower was rebuilt and the other was left as it was, as is noted here.
Another interesting dome as seen from near the lower end of the rue de Seine.
The Louvre attracts immense crowds during tourist season, so Pei's modern entry area that's mostly buried in one of the palace's courtyards was a necessity. Key is the buried part. Had this complex been at ground level, it would have destroyed the Louvre as an architectural composition. As can be seen in the photo, the interior space has no particular distinction. Moreover, it can be a bit confusing, though not so much as the rest of the Louvre.
I find the interaction of the stoned planes, the rounded building corner and the stairway interesting.
There is a modern building that can be glimpsed immediately uphill from this very Parisian edifice. Which do you prefer to look at?
Two door away is Guerlain's building. Beyond is yet another modern one that has more detailing than the modern building in the previous photo. Even so, Guerlain's shames it.
Finally, back along the Seine is one of Paris' top restaurants, the Tour d'Argent (Silver Tower). As this mentions, the restaurant and building are old, but the top floor with the large windows was added in 1936. I didn't eat here because I can't afford the food and probably wouldn't like it either. Plus, it was closed the day I took the photo.