  I have derived the Kretschmann scalar for a general black hole of mass m,
angular momentum per unit mass a, and electric charge Q. The Kretschmann scalar
gives the amount of curvature of spacetime, as a function of position near (and
within) a black hole. This allows one to display the "appearance" of the black
hole itself, whether the black hole is merely of stellar mass, or is a
supermassive black hole at the center of an active galaxy. Schwarzschild black
holes, rotating black holes, electrically charged black holes, and rotating
electrically-charged black holes, are all illustrated. Rotating black holes are
discovered to possess a negative curvature that is not analagous to that of a
saddle.
