Today I stumbled upon Microsoft’s 4K rendering of the Windows XP wallpaper Microsoft Design site has a ton of attractive wallpapers, retro and otherwise.

Best Sites to Download 4K/ULTRA HD Wallpaper on Windows PC. There are countless websites available on the internet which offer high-resolution wallpapers, which makes it challenging to choose.

Microsoft has a new desktop theme pack in the Microsoft Store. Not only does it have 4K images, but as far as we know, it's the first paid theme from the company.