  We revisit the geometry representing l collinear Schwarzschild black holes.
It is seen that the black holes' horizons are deformed by their mutual
gravitational attraction. The geometry has a string like conical singularity
that connects the holes but has nevertheless a well defined action. Using
standard gravitational thermodynamics techniques we determine the Free energy
for two black holes at fixed temperature and distance, their entropy and mutual
force. When the black holes are far apart the results agree with Newtonian
gravity expectations. This analyses is generalized to the case of charged black
holes. Then we consider black holes embedded in String/M-theory as bound states
of branes. Using the effective string description of these bound states and for
large separation we reproduce exactly the semi-classical result for the
entropy, including the correction associated with the interaction between the
holes.
