If you are interested in prehistoric monuments, you will certainly enjoy this one. Know your directions ahead of time as there was no signage that I remember (march 2018). You can see the dolmen on google maps, satellite view. It is a very short drive off N381, roughly one third of the way travelling from Redondo to Estremoz. I stumbled upon Megalithic Portal website while planning the trip and found it very helpful: you can see descriptions of megalithic monuments and their locations on the map; there are many in the area. This one is very well-preserved.
There was a wire (don't think it was an actual gate; I could be wrong though) on the ground as we drove closer to the dolmen on the dirt road. There was just one car with a couple of tourists and their guide that we met at the dolmen. Before they left, the guide asked us to close the gate on our way out. Just be careful; it is an electric fence for the cows, I'm guessing; don't get shocked.