Picasa 3, the (discontinued) Photo Editor and Viewer was such a great piece of software... There are some replacements (eg. can think of XNView for instance for viewing, and many more for editing...) but none come close to how user friendly Picasa was.
So for those, like me, who want to run this fantastic thing, even if it hasn't been updated in a long time, but still works like a charm, I have an old copy of the installer I am sharing here:
picasa39-setup.exe, 13,0 MB in size
I bet you can also find it on FileHippo.com, or some other archiving – file sharing service. But here it is anyway. Enjoy! ;-)
If using a deprecated software is not something for you but that you still need to browse high volumes of images scattered in directories, a quick and easy fallback back solution (even if it's not as nice) might be XnView:
choco install -y xnview