The Lyman-alpha forest - a dense series of ultraviolet hydrogen absorptions seen in the spectra of distant quasars - provides a unique observational probe of the early Universe. The number density of spectroscopically measured quasars at these vast distances has recently risen to a level that has enabled secure measurements of three-dimensional large-scale structure in the foreground intergalactic gas using the inhomogeneous absorption patterns imprinted in the densely sampled quasar sightlines. In principle, these modern Lyman-alpha forest observations can be used to statistically reconstruct three-dimensional large-scale structure maps of the early Universe over the massive cosmological volumes illuminated by current spectroscopic quasar surveys. However, until now, such maps have been impossible to produce without the development of scalable and statistically rigorous spatial modeling techniques. Using a sample of approximately 160,000 quasar sightlines measured across 25% of the sky by the SDSS Baryon Oscillation Spectroscopic Survey, here we present a 154 Gpc^3 large-scale structure map of early Universe - the largest volume large-scale structure map of the Universe to date.