Spine of the Gods
From Halopedia, the Halo wiki
The Spine of the Gods (also termed the unbreakable spine) was the nigh-unbreakable skeleton of the former-Covenant capital city-station, High Charity. The Spine of the Gods was primarily constructed from the remains of a derelict starship of Forerunner origin discovered orbiting the world of Tuluk'katho. The Fortress-class vessel discovered by the Covenant served as the basis for the station's construction and was most known as the core of the long "tail" that stretched below the station's superstructure, crowned at its apex by the keyship Anodyne Spirit. The Spine of the Gods sat at the very core of High Charity, and was said to have grown "cold, silent and inaccessible" multiple millenia prior to the city's fall in 2552.
The Spine of the Gods was said to "house elder engines", indicating that the Forerunner artifacts named the Wings of Malygus and Sefom Invictus (High Charity's maneuver drive and slipspace drive systems, respectively) were originally the Fortress vessel's engines. Constructed atop the Spine of the Gods were the Spires of Gifting and Lances of the Faithful - the docking umbilicals that served the station and the station's vast array of powerful weapons, respectively.