The galactic core is the region surrounding the black hole at the center of the Milky Way.
History
At some point between COUNTER/Weight and Twilight Mirage, the Divine Independence led an effort to move Earth from the Sol system to orbit the center of the galaxy.[1][2]
A Dyson sphere was later built around the galactic core, which generates nanomachines with the black hole's energy.[3] It was eventually abandoned by the New Earth Hegemony. Thousands of years after its construction, the core was overtaken by Perennial with the help of HORIZON and used to fuel the endless tides of the Perennial Wave.[4]
In the Road to PARTIZAN, a space station forms a vast horizontal shelf that goes around the black hole with a shield protecting it from the intense gravity; the 'sphere' is actually created by the invisible orbit of the nanomachines around the black hole.[5]