Cement Factory

Our guide Noah explained that the Maya made cement by heating limestone, then grinding it up and adding water and some other stuff (I was not listening carefully).  I believe this was one of the pits used for heating the limestone.  

(On a side note, the Greeks and Romans are really lucky so much of their building was done with granite and marble.  The Maya built with limestone which is soft and easily erodes.  I suspect huge amounts of Maya culture has been lost because the stone it was carved into literally dissolved.)