Antwerp has 2 other regularly used names: Antwerpen and Anvers.
Antwerp is the English name for the city. Antwerp's population is largely Flemish (Dutch) and they call the city 'Antwerpen'. Belgium's other major language is Wallonian (French) and they call Antwerp 'Anvers'. There is a third official language, German, but this is only the mother tongue of a tiny minority. Obviously, these alternative names weaken the domain's potential.
As English is very commonly spoken and it is a major city, I still believe this domain has value, particularly with a tourism, business or internationally focused organisation.