tall futuristic island city landscape concept art, huge white military fortress on a mountain peak, scifi Roman architecture inspiration, ((large dome structure, dome)), coast, ocean, colors, ocean skyline background, cliff, black tones, dark tones, scifi features, deep shadows, ((graphic novel sketch, black sketch lines, low-key cinematic lighting, thick ink outlines, digital oil painting, posterized, cel shading, vector illustration, tenebrism, bold brush strokes, subtle colors))