A black hole has a singularity at its center. A black hole is space-time volume surrounding a singularity where the curvature of spacetime is such that space and time are somehow flip-flopped. I.e. we are normally free to move in space, but move inexorably in one direction in time. Across a black hole's event horizon, that's flipped (or so the math predicts). Meaning we would be free to move about in time, but always inexorably moving in 1 direction - toward the singularity. (Y'know, math... sometimes you piss me off.)

I think of the singularity as the defining feature of the black hole, but not the black whole.


Good catch on this one:
What can it mean for a particle with no physical dimensions to rotate?
How would we know / what would we measure to determine whether or not it was rotating?

Now, let yourself move away from black holes and think about an electron. An electron has no measurable size, but we still talk about the spin of an electron. That's one reason I'm always quick to point out that QM spin is not other spins.

Aside from that, are you bothered by the center of a spinning rigid object?