The cave consists of a long cave formed mainly by collapsed buildings. It is the only way to Ulysses' Temple, due to buildings collapsing in the Divide. The buried buildings, comprised of a stairwell and two rooms, serve as a transitional area linking the cave to the Boxwood Hotel roof.
Eyebot upgrade circuit board - When facing the entrance of the cave from the clearing, detonate the nuke embedded in the rocks to the east. After the detonation, climb the beam on the ground marked with a blue old world symbol on it up to the blast site, and the circuit board will be on a destroyed eyebot lying directly ahead upon reaching the end of the beam.
A copy of D.C. Journal of Internal Medicine is located in the second room after entering the door to the Buried Buildings, between a toppled desk and chair, adjacent to a usable bed and a Ralphie poster.
"Abaddon" is an intensive form of the Hebrew word Abad, meaning "destruction." In the Biblical Book of Revelation, Abaddon is the name of a male angel seen in a vision as a king of an army of locusts. Considering the nature of The Divide, as well as its proximity to The Temple, this makes the cave's name a very fitting title.