Apollinaire uses liquid sounds to evoke the Seine River.
L’amour s’en va comme cette eau courante
L’amour s’en va
Comme la vie est lente
Et comme l’Espérance est violente
Vienne la nuit sonne l’heure
Les jours s’en vont je demeure
Passent les jours et passent les semaines
Ni temps passé
Ni les amours reviennent
Sous le pont Mirabeau coule la Seine
The "ooh" sound perfectly fits his subject. You don't have to be a Francophone to enjoy the sonority of this poem. In French, we talk about a distinction between forme (form) and fond (content, literally, depth or bottom). Sous le pont Mirabeau shows Apolinnaire to be a master of the art of forme.
Today, I bought a copy of Shakespeare's complete poems, including the sonnets.
Above, we can see a line of iambic pentameter in French: Et comme l’Espérance est violente. Of course, Shakespeare has the best command of sound of any English poet. The line Let me not to the marriage of true minds/ admit impediments" has been swirling through my brain. Count all the crisp t and d sounds! You can know a poem by its earworms.