Re: Super cities
Two quick things:
1. Not to speak for JmOz, but I don't think he is implying that the UN is a "superior" entity. Rather it is a result of negotiation, which implies a treaty or some other sort of agreement. Under the Constitution, the United States may enter into treaty obligations (which are superior to domestic law but not the constitution) with foreign countries or institutions. Those obligations may be binding and grant rights to those other entities (think about the various conventions and treaties granting diplomatic rights -- those countries then have jurisdiction over the premises of their embassy's as if those areas were part of the parent country). Quite frankly, so long as the Senate gave its advice and consent, I think the President, under its Article II powers over foreign affairs, would have sufficient authority to enter into an agreement with the UN to station super teams on US soil.
2. The UNTIL source book does a nice treatment of the international legal aspects of UN sponsored teams.