sentences:  These outstanding Roman cements are based on the calcic activation of ceramic aggregates (in Latin "testa", analogue to our modern metakaolin MK-750) and alkali rich volcanic tuffs (cretoni, zeolitic pozzolan), respectively with lime.MAS-NMR Spectroscopy investigations were carried out on these high-tech Roman cements dating to the 2nd century AD.They show their geopolymeric make-up.