Eleven hydraulic concretes from ancient Roman harbours around the Mediterranean seacoast were drilled by the Romacons team in 2002–2009. In 2008–2009 the same team extracted three new cores from a reproduction of a Vitruvian concrete pila, cast in seawater at Brindisi harbour in 2004, and previously cored at 6, 12 and 24 months curing. New geochemical and mineralogical analyses of representative ancient mortars, and the concrete reproduction in Brindisi, are summarized here. In addition, the progress of the pozzolanic reaction in the various hydraulic concretes is evaluated, through compositional and microstructural examinations.