I couldn't find a 4k version of the anniversary wallpaper, so I upscaled the no logo version posted by u/ItsJeremyJenkins for those anybody else who might be looking for a 4k version. :
430842 4K, digital art, game art, artwork, video game art, mountains, The Elder Scrolls V: Skyrim, digital painting, fan art, Talos, snow covered, landscape - Rare Gallery HD Wallpapers