  For Gaussian Spin Glasses in low dimensions, we introduce a simple Strong
Disorder renormalization procedure at zero temperature. In each disordered
sample, the difference between the ground states associated to Periodic and
Anti-Periodic boundary conditions defines a system-size Domain Wall. The
numerical study in dimensions $d=2$ (up to sizes $2048^2$) and $d=3$ (up to
sizes $128^3$) yields fractal Domain Walls of dimensions $d_s(d=2) \simeq 1.27$
and $d_s(d=3) \simeq 2.55$ respectively.
