  We consider modifications to general relativity by the non-local (classical
and quantum) string effects for the case of a D-dimensional Scwarzschild black
hole. The classical non-local effects do not alter the spacetime topology (the
horizon remains unshifted, at least perturbatively). We suggest a simple
analytic continuation of the perturbative result into the non-perturbative
domain, which eliminates the black hole singularity at the origin and yields an
ultraviolet-finite theory of quantum gravity. We investigate the quantum non-
local effects (including massive modes) and argue that the inclusion of these
back reactions resolves the problem of the thermal spectrum in the semi-
classical approach of field quantization in a black hole background, through
the bootstrap condition. The density of states for both the quantum and thermal
interpretation of the WKB formula are finally shown to differ quant- itatively
when including the non-local effects.
