Over the course of Allderdice’s near century-long history, this high school has undergone several renovations, with new additions being added and old features fading into the past.

These three acres carry a lot of history, some of which has been banished into the forgotten realm of Allderdice’s past. But, some of the most forgotten or unknown parts of a place can be the most interesting. 

This is the story of Allderdice’s hidden pool: 

Every day here at Allderdice, hundreds of students eat their lunch in the school’s cafeteria. It’s a pretty standard high school cafeteria, but what many students may not know while they are at the tables eating their lunch, is that they are sitting above a crater-like hole right beneath them. 

That crater? The emptied out old pool that Allderdice once used for years. 

“It sits right underneath the new cafeteria,” John Boehm, a former custodian, said. “The deep end starts around where the vending machines are, and short end is around where that little snack shop is.” 

John Boehm worked in Allderdice for 19 years, retiring just a few years ago in 2019. He remembers his time at Allderdice well. 

“I loved Allderdice, all the teachers were nice,” he said. “And the students loved me.” 

With those fond memories also comes an expansive knowledge about the building. 

“I know that building like the back of my hand,” he said. 

The old pool, now with pillars installed to hold up the floors above it, has been emptied and vacant since 1987, when Allderdice underwent a major renovation during its 60th anniversary. 

The pool, however, was not the only change Allderdice saw, Boehm says. Prior to 1987, the school cafeteria used to be on the 4th floor of the building, before it was relocated to its present day place during the renovations. 

In addition to that, the second floor engineering wing used to be part of the Allderdice gym. If you walk towards that part of the building, Boehm says, you’ll notice that at a certain part, the pattern on the floor changes. That is the defining line of where the gym used to be. 

But that isn’t the only relic of pre-1987 Allderdice. 

If you have ever taken the elevator-side stairwell and stopped on the third floor, you might notice a set of four large green doors that go nowhere, with blacked out windows above them. Those doors at one point in time led to the old gym, Boehm says. Today, they are not open to students. 

While some students are completely oblivious to its existence, even as they eat lunch just a few feet above it, the old pool has become a folk tale to others. 

Marissa DeFeo, a current student at Allderdice, has spent her fair share of time down there. 

“Every year for ‘take your kid to work day’ they would take us to the gym, and then give us some small art projects to do, and then they would take all of us down to the old pool,” she said. 

DeFeo’s father used to work at Allderdice as a field manager, leading to DeFeo having the chance to see Allderdice’s underbelly multiple times in elementary and middle school. 

“It’s really small, the way to get down there is tiny, you gotta duck down.” 

She said it is an intriguing place to go, but also quite a dirty one. 

“It’s definitely an experience,” she added with a laugh. 

Recently, The Foreword had the opportunity to go down and get a look at the area. Mr. Boehm, insisting we just call him John, was nice enough to lead me down there and check the place out. 

Our journey started on the side of Allderdice that faces Forward Avenue, where you will find a steep and rickety staircase that leads you down to a door of mystery, which on a typical day is locked. 

Once through the door, you will find the first of several rooms located underneath the school. This first room stores the emergency fire pump. 

“If there was ever a fire in the building, that pumps water through the building so that firemen can put the fire out,” he said.

Towards the back of this first room, you will see a small set of concrete stairs leading to an opened door. The stairs are covered in water, an evident sign of flooding on this level, and the water trail actually flows through a decent portion of the floor in the first room. John and I carefully walked up the stairs and through the door, and hooked a right and then a left, leading us to a long narrow hallway. 

“Right above us in the [first floor] central hallway,” John says. 

Indeed, this long, pipe-ridden corridor sits right underneath the first floor main hallway. While the hallway on the first floor can lead students to almost anywhere in the building, the hallway underneath, cramped and dirty, is ultimately a dead end. 

However, if you turn to your right, there is a doorless doorway and a narrow walkthrough you can go through. 

Through the doorway you will find several things, the first of which is an old, somewhat creepy looking  crawl-space, filled today mostly with dirt and rubble. 

The second, John nicknames “the old steps to nowhere” is a staircase sealed off by a ceiling today. The stairs, when they were accessible, led down to where the old locker rooms used to be. 

That door near the staircase goes to a mechanical room, which unfortunately was locked, and we did not have keys to that particular door, so we could not get inside. 

Out of this mini-room and into the second opening sitting right next to it leads us closer to the pool. 

The walkway to what I could call the second half of this floor is shallow, and filled with various obstructions. At almost no point in this corridor could you stand all the way up, so if you’re extremely claustrophobic, this might not be the journey for you. 

Once we made it through, we were only a few turns from the big reveal. On the other side of this floor you will encounter what’s left of the old pool filter.

The filter used diatomaceous earth, John says, which is derived from tiny fossilized exoskeletons of algae-like water plants called diatoms. 

“It’s the best kind of filter to have, it filters out the smallest particles.”

Indeed, diatomaceous earth has a very small particle size, high porosity, and a crystalline structure, making it regarded as one of the best choices in filters, despite its high maintenance. 

“A diatomaceous filter is the best kind of filter, but you have to wear a mask because of the bones, you don’t want that in your lungs.”

And at long last, where the pool filter’s skeleton lies, rests a carved out hole in the side of the wall. Step through that wall carefully, and you’re standing inside the pool. 

The emptied out gap where tons of water once stood is massive, and is crazy to stand in. The top of the pool is covered up by a new ceiling, and several large beams have been installed to hold and bolster up the new ceiling. 

The pool still features all the old markings from when it was active, and you can still see very small parts of the old bleachers that used to rest right above and to the side of the pool. 

It’s a surreal place to stand in, and quite the journey if you are ever granted the opportunity. 

A walkthrough video of the entire underground floor can be found here.