Find of the year! Vintage Printable has FREE high resolution images of botanicals, architectural prints, old travel posters, and all sorts of other lovely things (like the example above). There are dozens and dozens, maybe hundreds of gorgeous options. The illustrations are curated by Swivelchair, an anonymous biopharma worker.
The images have a high enough resolution, that you can print them up poster size and they’ll still look great — not pixelated or fuzzy. Print one out on the oversize printer at your local copy center, then frame it in a ready made option and you’ve got fantastic wall art on the cheap. See a great example here.