Newgrange was the first prehistoric site in Ireland to have its astronomical alignment widely accepted, and since its discovery in 1967 has remained the best-known astronomically oriented archaeological monument on this island. This chapter investigates the discovery of the winter solstice orientation at this key light-centred site. It proposes a possible new explanation for the astronomically oriented ‘roof-box’: that its origins can be found in a previously unidentified extension to the passage during a phase of enlargement. Additionally, the chapter attempts to answer several fundamental questions. Is it conceivable that knowledge of the solstice was retained in the local community from the Late Neolithic? Could the solar orientation at Newgrange have been observed before its modern discovery through excavation, perhaps more than once? Finally, to what extent may pre-excavation reports of a winter solstice connection with Newgrange have influenced the reconstruction of the monument’s ‘roof-box’ and outer passage?