More from Bak_teria: The information was sourced from Archport, a mailing list commonly used by Portuguese archaelogists.
Back in 2010 there was some kind of rehabilitation idea or project but I think the county of Sintra forgot about it. It's always the same, no one cares about a broken dolmen. Despite it could be classified as cultural heritage It doesn't bring much money to the community. That's the only reason that I can think of to understand the oblivion.
http://ml.ci.uc.pt/mhonarchive/archport/msg09260.html
http://ml.ci.uc.pt/mhonarchive/archport/jpgVHreHrkiZ9.jpg
Translating the words in his email message, he says:
"Dear archportians, I just wanted you to know how is the actual state of the dolmen of Pedra dos Mouros that I had the opportunity to visit with permission of the owner.
It is indeed regrettable that the most imposing tomb of the Lisbon region with about 5 meters high and classified as a National Monument since 1910 is now broken in half. But the law of gravity and the neglect of humanity are fatal. This is not a question of blaming someone, but we must bare in mind the inclination that the lone pillar was subjected over time, also the type of limestone, the shots made during the construction of the CREL road and the new node to the newly opened highway or even the recent small earthquakes, all of them contributed to its partial fracture and the final blow was the big fall that broke the stone in 6 fragments. Sure, someone could have intervened before, but we must also consider that there are so many property fires every day... Finally concluding in a more positive tone, the dolmen is not totally lost, just shattered and can be risen up out of the ruins if there is will and diligence of the citizens and of the proper authorities."
Something is not right. This message is just to keep things from messing up down the road