Great Moravia left its mark here not in Piešťany itself but on a rock spur above the Váh at Ducové, a few kilometres upstream, at the place called Kostolec. A Moravian lord built a fortified court there in the ninth century — dwellings, farm buildings, a church of his own with a small burial ground for his family and his retainers, the whole thing ringed by ramparts and a deep ditch. It was a centre of power and administration, and the farming and craft villages of the surrounding countryside answered to it. The excavated outline of its little pre-Romanesque rotunda — a round church — has been rebuilt on the spot, so you can stand inside the ground plan of a building that was in use before the kingdom of Hungary existed.Veľká Morava sa tu nezapísala v samotných Piešťanoch, ale na skalnom ostrohu nad Váhom pri Ducovom, pár kilometrov proti prúdu, na mieste zvanom Kostolec. V 9. storočí si tam veľmož postavil opevnený dvorec — obydlia, hospodárske budovy, vlastný kostol s malým pohrebiskom pre rodinu a družinu, a to všetko obohnané valmi a hlbokou priekopou. Bolo to mocenské a správne stredisko, ktorému podliehali roľnícke a remeselnícke osady v okolí. Vykopaný pôdorys malej predrománskej rotundy, čiže okrúhleho kostola, je na mieste vymurovaný, takže si dnes možno stať do obrysu stavby, ktorá slúžila skôr, než vzniklo Uhorské kráľovstvo.
