text: Carcassonne became strategically identified when Romans fortified the hilltop around 100 BC and eventually made it the colonia of Julia Carsaco , later Carcasum ( the process of swapping consonant is a metathesis ) .
simplified: Romans fortified the hilltop of Carcassonne around 100 BC and eventually made it the colonia of Julia Carsaco , later Carcasum .