  We present a construction of domain walls in string theory. The domain walls
can bridge both Minkowski and AdS string vacua. A key ingredient in the
construction are novel classical Yang-Mills configurations, including
instantons, which interpolate between toroidal Yang-Mills vacua. Our
construction provides a concrete framework for the study of inflating metrics
in string theory. In some cases, the accelerating space-time comes with a
holographic description. The general form of the holographic dual is a field
theory with parameters that vary over space-time.
