A team of astronomers using the Subaru and Keck telescopes on Mauna Kea has discovered giant, three-dimensional filaments of galaxies extending across 200 million light-years of space. These filaments, which formed a mere 2 billion years after the birth of the universe, are the largest-known structures ever discovered. They are studded with more than 30 large concentrations of gas, each up to ten times as massive as our own galaxy. These giant gas clouds are probably the progenitors of the most massive galaxies that exist in the universe today. Press release courtesy of Subaru Telescope, National Astronomical Observatory of Japan