  A well-instrumented Green Bank Telescope (GBT) operating at high frequency
represents a unique scientific resource for the US community. As a
filled-aperture, 100m-diameter telescope, the GBT is ideally suited to fast
mapping of extended, low surface brightness emission with excellent
instantaneous frequency coverage. This capability makes the GBT a key facility
for a range of cutting edge science described in this document, only possible
at these frequencies. We note that the ability to perform the necessary
observations is unique and highly complementary to the capabilities offered by
interferometers, and should be preserved. We argue that rather than divesting
from this exceptional resource, it makes sense for the US community to invest
moderately to maintain GBT operations and to instrument it in an optimal
manner, enabling it to become an extraordinary complement to existing and
future radio interferometers. Adequately instrumented, the GBT would be a
pillar for 20-115 GHz science in the US and the world.
