  Black holes whose near-horizon geometries are locally, but not necessarily
globally, AdS$_3$ (three-dimensional anti-de Sitter space) are considered.
Using the fact that quantum gravity on AdS$_3$ is a conformal field theory, we
microscopically compute the black hole entropy from the asymptotic growth of
states. Precise numerical agreement with the Bekenstein-Hawking area formula
for the entropy is found. The result pertains to any consistent quantum theory
of gravity, and does not use string theory or supersymmetry.
