Is there a way to get a report of the ads that have been shown to the visitors of my website? Not just number of ads and clicks, but actual content of the ads.
@closetnoc is correct, there isn't such log available to us (publishers).
www.google.com/adsense > Allow & block ads > Ad review center is probably all you need.
What the progress bar in the Ad review center shows
Report of the ads that have been shown to the visitors of your website could be a very, very long list and you could even find it is not very useful / interesting / is boring.
I am using Adsense Sandbox which gives you better result than galeksic answer(Don't mind it bro :) ).