Howto query taxonomy term level?

Hello

Has anybody an idea how to query certain term level in the taxonomy hierarchy?

example:
taxonomy – place
> terms – US, GB, …(menu item – state)
> > terms – NY, London, ..(menu item – city)
> > > terms – Rockefeller, South, ..(menu item – street)

the goal:
What I want is to have a menu with items: State, City, Street. When you click for example on the “City” item, then it supposed to query list of all items in the second level from the “taxonomy place” hierarchy.

Secondly, how can I find the parent term? Say, I’m in the London query, and want to know under what state it belongs to.

thanks in advance 2046