Louvre Museum Online - Explore the entirety of the Louvre's collection for free
John's Background Switcher - Switch backgrounds to trending imgur, reddit, tumblr threads
The Met - Official app of The Metropolitan Museum of Art
Wallcat - Enjoy a new, beautiful wallpaper, every day.
Sketchfab for Museums - Browse thousands of cultural artifacts in 3D and VR
Splashy - Breathtaking, auto changing wallpaper app for macOS, Windows, Linux, iOS & Android