The cave consists of a long cave formed mainly by collapsed buildings. It is the only way to Ulysses' Temple, due to collapsed buildings. The buried buildings, comprised of a stairwell and two rooms, serve as a transitional area linking the cave to the Boxwood Hotel roof. Sunflower Summers' diary, for the Nostalgia challenge, is located in a suitcase near Summers' remains, along the northern wall of the first chamber of the cave. A usable bed and a Ralphie poster are located in the second room and an Auto-Doc will be found near the exit.
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 flag, and the circuit board will be on a destroyed eyebot lying at the end of the beam.
"Abaddon" is an intensive form of the Hebrew word Abad, meaning "destruction." In the Christian Bible's Book of Revelation, Abaddon is the name of a male angel seen in a vision as a king of an army of locusts.