For those unfamiliar with the local skyline, that rectangular arch is La Defense, a business district outside of Paris.
In the Paris-ward direction, there is a reflecting pool with a sculpture installation of what look like giant children's toys, each ornamented with a blinking light. All the lights shift colors in a coordinated pattern, but slightly out-of-sync with each other.
The photos don't capture it properly. What appears as a uniform grey-blueness across the pictures was actually pretty calming and visually interesting.
This post's theme word is polysemous, "having many meanings." The sculpture is surely polysemous.