Galactic Federation Headquarters is the primary base of operations of the Galactic Federation. Not much else is known about the HQ except that it is also the headquarters for the Federation Police. Samus's X Parasite surgery occurred here, and it was referred to in the manuals of Metroid II: Return of Samus and Super Metroid as the destination that the ambushed research SR388 crew of the Space Research Vessel Marina were attempting to reach. The manual for the NES Metroid states this research vessel was heading for Earth, implying that Federation HQ is located on Earth.
The introduction of Metroid: Samus Returns states that the Galactic Federation Special Squadron had lost contact during their mission on SR388, but "not before transmitting a small sampling of data back to headquarters." In Metroid: Other M and the Metroid: Other M Art Folio, it is revealed that Samus spent some of her time training with the Galactic Federation under Adam Malkovich here. It appears to be floating atop a man-made island, thought not far from land.