History.

It really was a good thing that the
Americans chose Berlin for president Kennedy,
when he went there way back.

For example:
If the had chosen Frankfurt.
He would have said.

Ich bin ein Frankfurter.

And worse.
If they had chosen Hamburg,
He would have said.

Ich bin ein Hamburger.

And for some strange reason, he never went to Wienna.


Hmmmm?