The appearance of the first stars and galaxies at the cosmic dawn represents a transformational yet unexplored episode of the Universe's history. I will present the measurement of an absorption feature in the sky-averaged radio spectrum centered at 78 MHz by the EDGES Low-Band experiment. This feature is broadly consistent with the absorption of photons from the microwave background by neutral hydrogen gas in the intergalactic medium at z~17 due to significant star formation about 180 million years after the Big Bang. If independently verified, this measurement could correspond to the signature of the cosmic dawn. However, the large amplitude and sharp profile of the measured feature are in tension with standard physical models. In my talk I will describe the EDGES Low-Band measurement of the radio spectrum over the range 50-100 MHz, which was conducted from the desert of Western Australia, as well as some of the proposed physical implications if the signal is confirmed to be of cosmological origin.