Stone walls, grey battlements, and a watchtower's shadow.
Citadel is a cool grey, close to blue.
It can be described as cool, muted, greyish and dusty.
Set in black, because black reads best on it.
A citadel is the most fortified area of a town or city. It may be a castle, fortress, or fortified center. The term is a diminutive of city, meaning "little city", because it is a smaller part of the city of which it is the defensive core.
Read on WikipediaCitadel is an American spy action television series created by Josh Appelbaum, Bryan Oh, and David Weil for Amazon Prime Video with the Russo brothers acting as executive producers. It stars Richard Madden and Priyanka Chopra as secret agents Mason Kane and Nadia Sinh who, after being attacked by members of a rival agency and having their memories wiped, must reclaim their lost identities and fight back.
Read on WikipediaNoun