  We present a derivation of the Bekenstein-Hawking entropy from conformal
field theories. In particular we consider a six-dimensional string
configuration with background metric AdS_3 * S^3 near the horizon. In addition
we introduce momentum modes along the string, corresponding to a
Banados-Teitelboim-Zanelli (BTZ) black hole in the anti-de Sitter (AdS)
space-time, and a Taub-NUT soliton in the transverse Euclidean space,
projecting out a discrete subgroub of S^3. This spherical part is described by
a SU(2)/Z(m) Wess-Zumino-Witten (WZW) model. The AdS_3 space-time, on the other
hand, is determined by two conformal field theories living at the two
boundaries: One SL(2,R)/U(1) WZW model on the horizon of the BTZ black hole and
one Liouville model at infinity. The extremal BTZ black hole interpolates
between these two conformal field theories. Moreover, we argue that the sum of
the three conformal field theories yields the correct microscopic
state-counting including all alpha' corrections.
