As with many sites in Bahrain, I found this difficult to find at first. I gave up trying at my first attempt. During my last afternoon in Bahrain I had some time left and decided to try again. And this time with success: it is actually quite easy, there is a sign "Saar Archeological Site" from the main highway between Manama and Saudi Arabia. The mistake I made the first time is to get off at Saar village - but that's a sprawling town where you'll never find it. You just have to wait for the next exit from the highway.
The only other creatures around at this dusty site were a policeman and a couple of dogs with puppies. I was a bit scared of the dogs at first, but the guard waved me in. The site is quite extensive, and with clear roads has the feel of a village. Unfortunately I did not have much background info on me, and there's only a small interpretative sign at the site itself