London, obvious
Rome, also obvious
New York? NYC isn't actually the capital of anything, but it's a major world city and a lot of wealth flows through there (for another definition of the word)
Possibly Note, as in a banknote? It's weak, but I don't see any other words which are less tenuous.
I wonder about Capital in the other senses of the word after that, but all of these feel pretty tenuous. So perhaps LIMOUSINE (people with a lot of Capital use)?
NEW YORK has a lot of capital running through it?
Capital takes the form of NOTEs?
Capital letters LINK sentences together? (especially tenuous)
I think of all our suggestions, I like ROME and LONDON best. Then NEW YORK -> NOTE -> LIMOUSINE, in that order. Thrawn, you are right that LINK is probably off, I was grasping at straws there.
I'm not super seeing WASHER or LOCK as much as the above, although I'd be open to persuasion. The first two are incredibly safe, we can probably lock them in.