  We show that the D-brane configurations for the five and four-dimensional
black holes give the geometry of two and three-dimensional ones as well. The
emergence of these lower dimensional black holes from the D-brane
configurations for those of higher dimensions comes from the choice of the
integration constant of harmonic functions, which decides the asymptotic
behavior of the metric and other fields. We show that they are equivalent,
which are connected by U-dual transformations. This means that stringy black
holes in various dimensions are effectively in the same universality class and
many properties of black holes in the same class can be infered from the study
of those of the three-dimensional black holes.
