Simplify the following text for a Grade 11 native English-speaking person.
Original: 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 .