Folder of the Default Windows Desktop Backgrounds
You may want to add some pictures to the default desktop backgrounds or to copy some of the default backgrounds to your pictures folder to create a better slideshow. You may even just like to browse easily your backgrounds folder, or configure a backup job.
Windows won’t let you know in the System Settings panel where default backgrounds are located, but it’s not a secret.
Open Windows Explorer and navigate to \YourSystemDisk\Windows\Web\Wallpaper