Menachite portal complex

"We did not discover the full extent of those ruins and likely never will."

- Dr. Catherine Elizabeth Halsey

The Menachite Forerunner Complex, referred to as a "temple" by the Covenant, is an underground facility built into Menachite Mountain on Reach by the Forerunners to house the Forerunner crystal.

Entrance
The outside of the complex resembles granite rock, with passages allowing access along the wall. The wall has a long stretch of glyphs trailing along it that twist into a spiral mosaic and vanish into ever-smaller curls. The glyphs are part of the wall's material, described as being composed of glittering mica inclusions in the granite matrix. The glyphs themselves are a series of squares, triangles, bars, and dots, and blur out of focus when someone looks at them directly.

When SPARTAN-104's blood touched the wall, a transformation occurred. The glyphs began to emit a soft red glow comparable to heated metal. The glow spread outward from point at which his blood touched the wall, and the colors in the center began warming to orange and then to yellow-gold. A single white glyph, a triangle, became visible in the center of the spiral. Despite the emission of light, the glyphs did not radiate heat. When SPARTAN-104 touched this glyph with his bare fingertip, all the glyphs along the entire wall glowed white with brilliant illumination. After a moment, the wall itself rumpled and transformed into a corridor leading into the complex.

The corridor was twenty meters in height, leading inward at a straight line that gently sloped deeper into the ground. Golden light shined from the ceiling. The floor was paved with asymmetric blue tiles patterned in a way comparable to waves lapping on a shore. The utterly smooth walls were inlaid with centered four-meter tall gold glyphs made of similar shapes of triangles, squares, bars, and circles. When the glyphs began to softly glow, SPARTAN-104 felt himself attracted to them, but resisted his impulse to approach them on an intuitive suspicion that they were dangerous. His radiation counter briefly pulsed, supporting his hesitation.

Further down the corridor, the ceiling stops shining golden light and fades to total black. Pinpoint lights emerge imitating stars, which twinkle realistically. In addition, silver-grey orbs that represent moons pockmarked with craters spin in wide orbits across the ceiling. Along the walls, tall green bamboo-like stalks appear. Dr. Halsey determined that these apparitions were semisolid holograms with no visible emitters.

Throughout the length of the corridor, the holography undergoes three transformations to depict different scenes, each sharing the golden glyphs along the walls. After the initial scene, it changes to depict an arid moonscape with deep craters and sterile light. It then transforms into a volcanic world with active streams of lava flowing along the walls. The realism of this scene is enhanced with realistic distortion of the air, which wavers as it would in the presence of extreme heat.

Main chamber
The corridor empties onto a landing overlooking an approximately circular room with a diameter of three kilometers, the center of which contains a flickering pedestal that holds the Forerunner Crystal. The landing is on one of twelve tiered levels that have no railings and encircle the room. The floor, approximately one hundred meters beneath the landing, is made of innumerable blue tiles that appear to shift around into patterns SPARTAN-104 describes as "frustratingly familiar". Unlike the floor in the corridor, these tiles form squares, circles, bars, and triangles. The ceiling is a dome with a holographic golden sun, a dozen moons, blue sky, and cottony clouds that morph into geometric shapes such as spheres, pyramids, bars, and cubes.

When Dr. Halsey and her Spartans approached the pedestal, they experienced spatial disorientation in which their path was distorted. Despite their attempts to reach the center as a close group, they found themselves heading off in separate directions. SPARTAN-104 described feeling a sense of vertigo as if he was walking on the ceiling instead of the floor. A test of rolling a ball bearing on the ground showed the floor initially sloped toward the center, but shifted around as the ball bearing rolled until it came to a total stop. SPARTAN-087 was able to intuitively determine the true direction toward the pedestal, ostensibly the opposite direction. The pedestal in the center is made of the same gold material as the symbols in the corridor. Above it floated the Forerunner Crystal, which spun and pulsed a bright glow of sapphire-blue light.

History
The Menachite Forerunner Complex was created in prehistory by the Forerunners. Their exact reasons for doing so, other than to hold the Forerunner Crystal, are unknown. After humans colonized Reach, they tunneled into the mountain for purposes of mining its rich titanium content. The Office of Naval Intelligence took over the mountain after the mine was built and installed CASTLE Base into the tunnels originally created for the mine.

Colonel James Ackerson of ONI knew of the existence of the Menachite Forerunner Complex, and made uncovering its secrets a secret project. He was, however, unable to learn of its entrance. The entrance was later discovered by SPARTAN-104 by accident and his group gained entry into the complex.

When the Covenant invaded Reach, they began digging into the mountain in search of the crystal. Dr. Catherine Halsey, along with SPARTANs 030, 039, 043, 087, and 104, fled the endangered CASTLE Base and into the remaining mine tunnels. There they discovered the outer part of the complex and managed to gain entrance. Just after they took the Forerunner Crystal, Covenant forces successfully blasted their way into the complex, and Covenant infantry killed Isaac and Vinh, although the others managed to retreat into a deep tunnel. After several hours, John-117 along with a small human force assaulted the main chamber with a captured Spirit dropship. They managed to rescue the remaining Spartans and Dr. Halsey, and then outran thousands of Covenant soldiers trying to capture the Crystal.

Trivia

 * The spatial distortion effects near the center of the main chamber may have been generated by a baffler, a Forerunner device used to create geometric distortions to hide an artifact or a location.