I once accidentally came across folders within Windows which contained old photos from my iphone which must have synced with my PC when I connected my phone to my PC / i-tunes.
I cannot find these folders now.
Added (1). I know how to get to App data > Mobile Sync > Roaming > backup.
However, the photos aren't there to open. They are strange looking files which you cannot do much with.
Read more:
Where are my iphone photos stored in my PC?