National Geographic website is one place where you can download some quality wallpapers for your desktop. National Geographic has a “Photo of the Day” wallpaper option and if you liked these wallpapers you can download them easily using GeoNatGet. It is a freeware tool which helps you in downloading wallpapers from National Geographic website based on year and month.
You can select the year and month from the box and click the get links and the app list out all the links for “Photo of the Day” wallpapers. There is no option to download it directly or automatically. The app populates only the links and you need to manually download them.
You can try out NatGeo Downloader which helps you to download all the wallpapers automatically.