une atmosphère des plus romantiques ou une atmosphère de plus romantique

Question

Why is the superlative in the plural, when the subject is singular?

Cécile Janty-Davies · Accepted Answer

Hi Ian, 
No, it is always in the plural as you are comparing it with others:

une ambiance des plus chaleureuses = one of the warmest ambiances 
un gratin des plus succulents = one of the most succulent gratins ( bakes) 
un portrait des moins flatteurs = one of the least flattering portraits

I am not 100% about the English translation so if anybody wants to comment I'll happily change it.
Bonne Continuation

andy f · Answer

I think what i.l was asking was confusion between l atmosphere la plus romantique (the most romantic atmosphere) and here, which is the atmosphere the most romantic of all the atmospheres.  I had the same confusion until I read the question and answer so thanks