  We present an overview of the GOTHAM (GBT Observations of TMC-1: Hunting
Aromatic Molecules) Large Program on the Green Bank Telescope. This and a
related program were launched to explore the depth and breadth of aromatic
chemistry in the interstellar medium at the earliest stages of star formation,
following our earlier detection of benzonitrile ($c$-C$_6$H$_5$CN) in TMC-1. In
this work, details of the observations, use of archival data, and data
reduction strategies are provided. Using these observations, the interstellar
detection of propargyl cyanide (HCCCH$_2$CN) is described, as well as the
accompanying laboratory spectroscopy. We discuss these results, and the survey
project as a whole, in the context of investigating a previously unexplored
reservoir of complex, gas-phase molecules in pre-stellar sources. A series of
companion papers describe other new astronomical detections and analyses.
