Nesactium (Istrian dialect: Vizače, Croatian: Nezakcij, Italian: Nesazio) was an ancient fortified town of the Histrii tribe. Its ruins are located in southern Istria, Croatia, between the village of Muntić and Valtura.
In pre-Roman times Nesactium was the capital of the indigenous population of the peninsula called Histri, connected to the prehistoric Castellieri culture. There are some theories stating their Celtic background, but who they were and where they came from has never been discovered for certain. Supposedly their main economic activities were trade and piracy all over the ancient Mediterranean Sea. All indicates they were a particular ethnical group, such as Etruscans in Italy.
In 177 BC the town was conquered by the Romans and burned. Rebuilt upon the original Histrian pattern, it was a Roman town until the 7th century AD, when it was destroyed. Its Illyro-Roman walls still remain.