Powerful person's suggested built-up area is like Dún Laoghaire in the old days? (9)

'like dun laoghaire in the old days?' is the definition.
I don't know anything about this answer so I cannot tell whether this works.

'powerful person's suggested built-up area' is the wordplay.
I cannot quite see how this works, but
'person's' could be 'kings' (king is a kind of person) and 'kings' is found within the answer.
'area' could be 'town' (town is a kind of area) and 'town' is found in the answer.
This accounts for all the letters.
This explanation may well be incorrect...

'is' is the link.

Can you help me to learn more?