Bing homepage gallery which I think is your official web. Here is the information I save about that particular image: DeauvilleUmbrellas_FR-FR10404668741_2013-0831
Here are the web that I am always checking :
istartedsomething.com, Bing homepage gallery, Bing wallpaper archive, Bingwallpaper.anerg.com
Bing wallpaper archive, Bingwallpaper.anerg.com
This particular http://bingwallpaper.com is only for the current month, like November.