  South Pole Station offers a unique combination of high, dry, stable
conditions and well-developed support facilities. Over the past 20 years, a
sequence of increasingly sophisticated CMB experiments at Pole have built on
the experience of early pioneering efforts, producing a number of landmark
contributions to the field. Telescopes at the South Pole were among the first
to make repeated detections of degree-scale CMB temperature anisotropy and to
map out the harmonic structure of its acoustic peaks. More recent achievements
include the first detection of polarization of the CMB and the most precise
measurements of the temperature power spectrum at small angular scales. New CMB
telescopes at the South Pole are now making ultra-deep observations of the
large-scale polarization of the CMB and of its secondary temperature
anisotropies on arcminute scales. These two observing goals represent the
current frontiers of CMB research, focused on constraining Inflation and the
nature of Dark Energy. The South Pole now hosts an array of CMB observing
platforms covering a wide range of angular scales and supporting very long
integration times on the cleanest sky available, and thus should play an
increasing role in pushing these frontiers of CMB research.
