I call these designs Art Nouveau in the title although really they're a little late to be truly Art Nouveau.
These wonderful pictures come from a 1917 design book and they're truly scrumptious - and, as far as I can tell, out of copyright.
The central illustration in this last picture looks like something out of Dr. Who!
I'll have to try and think of how to use these - and there are loads more too including some nice posters (I just LOVE vintage posters!).