  We present a magnetically shielded environment with a damping factor larger
than one million at the mHz frequency regime and an extremely low field and
gradient over an extended volume. This extraordinary shielding performance
represents an improvement of the state of the art in damping the difficult
regime of very low-frequency distortions by more than an order of magnitude.
This technology enables a new generation of high precision measurements in
fundamental physics and metrology, including searches for new physics far
beyond the reach of accelerator-based experiments. We discuss the technical
realization of the shield with its improvements in design.
