I wouldn't call a giant symbol dominating every gate in the Imperial City subtle.

Not only was it on Morrowind's cover, it is also present on the http://www.uesp.net/wiki/File:MW_Armor_ImperialDukeM.jpg The belt of the Imperial Legion and Dragon armor in Oblivion, as well as on the shield of the statue of Tiber Septim (I think that's him) in the marketplace district. :thumbsup:
I couldn't find a good image of the latter three, so you'll have to go in-game yourself to see those. :unsure: