Er, Pittsburgh, that is.

The AOTC is a group of living humans (less than the population of Earth; could be just the one person but not likely, and could be unisex but not likely) who have been around a long time in some form or other; who share a common country (which could be the UK but not necessarily; they could be found in Pittsburgh, PA); who could be a family but not necessarily so; who share a common goal but a rather undefinable one, and could be said to gather in one place from time to time (but this would be a very strange way to describe it). You could become a member of this group just by being born.
The people in this group do not change from day to day, and they are not mythical, the staff of a business, a group of musicians (though this isn't excluded by the answer), the Tories, the Mafia, the heads of the Commonwealth, people who observe something, MCers, an orchestra, travelling football supporters, shareholders at an AGM or people who share a birthday, and are not connected with politics, a game, railways, food, an astronomical event, booze, shopping, queueing or royalty (well, could be, but extremely unlikely), and who are not intended to be rats or prats but could be.

(Tuj) NO - no typical physical or medical trait.