In the center of a black hole is a gravitational singularity, a one- dimensional point which contains a huge mass in an infinitely small space, where density and gravity become infinite and space-time curves infinitely, and where the laws of physics as we know them cease to operate.

In a black hole is something, what we don't know, because the mathematics, which we use to describe it, shows us only a zero-dimensional point (one dimension woudo be a kind of "string" and not a point), which contains the complete energy of the black whole. As far as I know a black hole is outside of the event horizon completely determined by its mass, electric charge and torque moment.