For a moment, Kate worried that the mysterious intercom voice would soon direct her to participate in one more ill-conceived rehash of the infamous 50s-era superconductor experiment; and what he said next partially confirmed her fears.

"hmm...I can not seem to get the exit door to respond. It keeps complaining that there's not enough input. I think I have an idea, though. Can you go back to the control room and power the um.. superconductor on? The big machine in the middle between both rooms- I think a good jolt from the front of that thing might be what I need to coarse the door into submission. Might be worth a shot, don't you think?"

No. Absolutely not. Not in a million years, Kate protested silently to herself.

"..uh- sorry, I keep forgetting I can't hear you right now. So I'm going to assume that was a..yes. I think."

Kate facepalmed. If her vocal cords were still functional, she would have also groaned with annoyance. Instead, she begrudgingly re-entered the control room through the portals she had placed several minutes ago.

Searching for a way to power up the machine, kate found a large button on a pedestal near the broken observation window. Beside the button, there was a small readout that glowed a burned-orange color, with the word "Standby" clearly visible- an indicator that the system was ready to fire, despite being dormant for a decade or more. Anticipating the worst, Kate clenched her teeth and pressed the button.

Immediately, the machinery rumbled to life with the loud sound of a colossal motor spinning up and energy charging, ready to blast out of the machine's front end any second. Unfortunately, the entire room also rumbled, knocking loose a couple of the broken window's remaining shards and several layers of dust from the walls, which caused kate's eyes to become irritated. As she squinted, holding back tears, she could see the front dish of the superconductor begin to rotate, and arcs of electricity began to form in front of the machine's operational end. Realizing what was about to happen, Kate quickly wiped her eyes, dashed through her portal, and pressed herself tightly against the exit door in the other room, which was a huge pressure-sealed door similar to the one she had initially entered this sector through.

For a moment, the air seemed to become eerily colder- then, with a deafening bang, a continual beam of artificial lightning erupted from the colossal machine, striking the receiver dish in the wall with a shower of sparks.

Every hair on Kate's head stood up on end as the air crackled with electrical energy. As the voice had guessed, this proved to power the exit door wide-open. Kate didn't hesitate for even a moment to leap through the door- She wanted to get away from the beam of raw power as quickly as possible. The machine powered down a few moments later, and the door slammed shut behind Kate.

She took a deep breath of relief. After picking herself up off the floor, she attempted to brush her hair back into shape with her hands. In front of her, there was another short hallway, nearly indistinct from the one she had traversed earlier. With oil stains on the walls, dust on the floor, and more inexplicable wooden crates scattered around, the hallway gave Kate the feeling that the Proto-Enrichment-Center just ahead had been dormant for quite some time indeed. However, what she found puzzling was that the lights were on. Once again, the intercom voice spoke.

"Woah, alright- that was a little more power than I expected. I almost blacked out for a second there...What kind of batteries are on that thing!? ...anyways, it looks like my idea worked. Can you enter the waiting room up ahead? You are almost to an area where I can see you. I've already gone and re-routed the energy to this area, but I need you to throw the main breaker for me to enable the cameras."

Kate proceeded through the door at the end of the hallway and arrived in a room decorated with several folding chairs. The words "Test Subject Waiting Area" had been stenciled on the wall to her left next to the entrance door, and she could faintly hear a piece of generic-sounding Jazz music emanating at a relaxed pace from an unseen speaker somewhere in the room.

To Kate's right, a stylized poster hung depicting a building that she recognized from an old photo as a portion of Aperture's original surface-level offices and a handful of consumer home-computing terminals from the era. Amusingly, the poster featured a spelling error of the company's name in several places. Not only was the mistake visible on a sign in front of the building, but also on the building itself and in the main header. The header proudly advertised one of Aperture's many slogans:

"Aperature Laboratories, a clear focus on the future." The typo was made funnier to Kate because the company name was spelled correctly in only one place: The small logo in the bottom-right corner. She got the sense that there had been abysmal management in charge when the poster had been designed.

At the opposite end of the room, an l-shaped control desk seemed to have served as a reception desk at one time. The remnants of a long-dead potted plant stood nearby, leaning against the desk now covered with dust like everything else in the room. Behind the desk, Kate found an old newspaper comic strip taped to the wall by whoever once operated the desk. She recognized it as an early installment of "Doorfeldt"- Aperture's darker-humored in-house knockoff of a more well-known comic. In this strip, the titular character Doorfeldt the cat had been knocked out with neurotoxin after his owner angrily discovered him having just eaten the last of his lasagna.

Aside from the long-gone employees' bad taste in comedy, The room would almost feel oddly cozy if not for the ominous darkness on the other side of a window in the wall opposite the entrance.

Directly to the left of the window, kate found a breaker switch unmistakably labeled "MAIN POWER" in bright-orange paint. To the left of the breaker switch, another door with a keypad led into the mysterious dark room. Without hesitating, kate grabbed the lever and threw it upwards. A distant generator engaged, and after a moment, the entire space behind the glass became brightly illuminated by an array of stadium-sized lights, which were mounted only 10 feet above the floor, give-or-take. It seemed excessive to kate, but she didn't give it a second thought before she spotted something moving on the wall inside the room- A security camera slowly rotated to face Kate through the dirty glass window.

Noticing Kate's yellow-and-black jumpsuit (colored differently from standard test-subject uniforms to distinguish her as a scientist when she volunteered for occasional tests), The intercom voice exclaimed, "What!? Its Y- er, I mean- wow, you..are..actually a human, uh- surviving, down there! I wasn't actually sure until now, but great!"

Kate half-smiled. Although she still wasn't sure the owner of this voice could be trusted, she couldn't help being reminded of one of her colleagues. One of the other lab techs who formerly worked with her sometimes stumbled over his words when excited about something, and the resemblance seemed uncanny. Kate almost pondered if this was indeed one of her co-workers speaking to her from some control room higher in the facility, but soon, the voice identified itself as somebody else entirely.

"Well, now that I have identified you, I guess I should introduce myself. My name is David, and- at least for the time being- I am overseeing some of the lower sections of this facility. A lot has happened recently, but I can't explain it right now- It will be safer to explain it when we meet face-to-face. For the time being, though, I will guide you through these old tests- Inside the chamber, you should see a large steel pipe near the ceiling. Follow that, and I will tell you more soon. Sound alright?"

Kate didn't like the sound of that. She suspected something wasn't quite right, and this 'David' guy seemed reluctant to say too much, as though worried that somebody was listening in who he would rather not be.

She acknowledged David with a nod in the camera's direction, then entered the newly illuminated test chamber. The walls were lined with perforated square metal panels, each painted in various dull brownish-green and gray colors, unlike the newer test chambers that Kate was familiar with seeing whenever she visited the modern Enrichment Center. Instead, the walls were constructed from solid metal blocks in the more recent tests, aside from locations where Portals were intended to be placed, where they were made of concrete panels.

However, the dust-stained floor was made out of concrete tiles, the same as the modern tests.

Above, through the grated roof, she could see a much larger room outside the small test chamber. Near the ceiling, Kate saw a gigantic steel pipe looming above- this was likely what David was referring to, she noted.

Refocusing on the inside of the chamber, Kate found a weighted cube sitting on the floor near a standard Aperture Science Heavy-Duty Floor Button. It was a simple introductory test, and utilizing her portal gun's zero-gravity lifting mechanism, Kate lifted the cube onto the button with ease. The lights suddenly shut off with a shower of sparks, only to power back on a moment later, followed by the test's exit door sliding open. The door was a sleek metal panel hung on an overhead rail from motorized wheels.

"Uh- I should probably let you know that the wiring might be a little bit weird in this place. There might be a few minor malfunctions, but don't be too alarmed about that; I can probably work my way around anything that goes wrong," David warned.

Kate found herself on a walkway that snaked its way through the warehouse-like room on the other side. The walkway had a couple of endpoints, leading to more of the proto-test-chambers. From outside of these rooms, Kate could see that they were built in a semi-temporary fashion. The panels and other modules appeared to be designed for easy removal or adjustment, having been slid into place between an array of permanent support beams.

Aside from this proto-enrichment-center's thermal-insulated ceiling, the walls had been roughly hewn from solid rock, as many areas in these lower sections of Aperture often were, except one wall- which had been constructed from corrugated metal panels, painted in a brown color.

With some additional guidance from David, Kate found an elevator and boarded it. A cheerful jingle played from a tiny unseen speaker, then the elevator started to rise- but abruptly stopped next to the giant pipe above. As a pneumatic piston of some sort engaged above her, Kate noticed a large sign bolted to the pipe, which read:

"MAINLINE THROUGH TUNNEL CR-01," with an arrow pointing along the pipe's length. Soon, the elevator changed direction and began moving along a ceiling-mounted rail into a dark tunnel adjacent to the hulking mainline.

After several minutes, Kate heard David speak through the same tiny speaker that the jingle played through previously.

"Alrighty. If my schematics are at least somewhat accurate still, you should be on your way to Section B... hmm..."

David paused as though he were leaning into the computer screen that Kate imagined he was seated at.

He continued, "... is that a...what is that? Uh.. ok, miss..whatever your name is. There was a hole in my map here, so I looked up what these tests were last used for, aannd...it looks like something they called an 'Aperture-science 4000-megawatt heavy-duty abrupt rejection button'. Honestly, I have no idea what that is, but the only way out looks like it will use it, so please be really careful."

At that moment, the transport elevator emerged from the tunnel into another cavernous room. To the left, the mainline pipe also re-appeared.

The overhead rail of the elevator began to turn to the right, towards a suspended platform, high above a gigantic pool of acid below. Another set of proto-test-chambers was built within the area, but these seemed more extensive than in the previous section.

As the elevator passed before the first test, Kate saw a weighted cube float through a delivery tube connected to the room. Then, through a large hole in the paneling, Kate noticed the cube land inside the chamber, beside an odd-looking round device bolted to the floor, which she could only guess was the "Rejection Button" David had mentioned. Before she could get a better look, the elevator arrived at the suspended platform just outside of the test chamber, and the cage-like door creaked open as another cheerful-sounding jingle emanated from the speaker.

Kate stepped out of the elevator and onto the suspended platform, and as soon as she was clear of the transport, the departure jingle sounded once more, and the elevator began moving back in the direction it had come from.