Upping the Anta

A dolmen in Portugal is called an anta, and there are plenty to see, many of 
them in poor shape, having been used by shepherds and others for millenia; 
the largest of all known dolmen (in the whole wide world) is just a few miles 
out of Evora, near Valverde, the Anta Grande do Zambujeiro

They're doing some work on it, so it is covered by this enormous tin roof; the 
roof was a bit of a comfort, however, since it was raining hard, and the site a 
mile down a track from the (paved) parking; Vicki didn't come along for this 
one, so I can provide little measure in perspective; the major up-rights are all 
about 25 feet in height...as big nearly as any standing stone we have seen

Up closer

Part of the enormous but very thin capstone/roof

Interior view

Nothing I have ever seen among dolmens and similar structures compares in size with this. Like the Almendres, it has an estimated date of 5,000BC.