Dominion Headquarters was a Central Command facility on Cardassia Prime from which several senior Dominion officials, Cardassian Legates Dukat, Damar and Broca, the Female Changeling, and several clones of Weyoun directed the war against the Federation and its allies from mid-2374 to late 2375 following the fall of Terok Nor.
A high-security facility, the main doors were composed of neutronium, making them impervious to conventional explosives. The interior was rather spartan, with minimal decorations other than the Dominion and Cardassian logos. The main room featured a large monitor where the Female Changeling and others could communicate with commanders as well as observe fleet movements. Each official had their own quarters, including the Female Changeling. In late-2375, she had a secure communications system installed so she could conduct secret negotiations with the Breen.
During the final hours of the war, forces from the Cardassian Rebellion, led by Damar, stormed the headquarters. Though several Cardassians, including Damar himself, were killed during the assault, resistance members Kira Nerys, Elim Garak, and Ekoor managed to secure the facility and capture the Founder. There, Odo came to convince the Female Changeling to order Dominion forces to stand down, and she agreed. (DS9: "What You Leave Behind")