Are there any artworks based on the Adamantium tower in Imperial City?

you mean white-gold? Might be some fan-art of it, but I don't know of anything that just depicts the tower/city.

theres always Oblivion the collector's edition comes with some concepts of the city, though they are almost exactly like the finished version.

If you mean the Adamantine tower, not the White-Gold, it was in Daggerfall as a http://www.imperial-library.info/realms_iliac/xanarticle2_castle_balfiera.jpg.