Quiz: What links the capital cities of Montserrat and Palau?

(Please use spoiler tags for answers.)

@icecolbeveridge My first thought was they were both destroyed by volcanic eruptions (I know this for sure about Plymouth, Montserrat) but I googled for Palau and it turns out it has no population or at least a very tiny one, so the answer has to be along the lines of Nobody lives there.
@vpunt Correct - they're the only capitals (afaict) with an official population of zero. Good work!