This is the 14822nd most frequent German word.
prominentestes
"Most prominent."
Here, 'prominenteste' is used as a superlative adjective to rank the cathedral as the most prominent among other buildings.
Das prominenteste Gebäude in der Stadt ist der Dom.
The most prominent building in the city is the cathedral.
In this sentence, 'prominentesten' illustrates a plural superlative usage to describe Mrs. Schmidt's status among the other members.
Eines der prominentesten Mitglieder des Vereins ist Frau Schmidt.
One of the most prominent members of the club is Mrs. Schmidt.
Here, 'prominenteste' refers to the primary or most noticeable characteristic of the described device, used as an attributive adjective.