A London couple have shared the incredible discovery they made while renovating their new apartment—a hidden basement.

Caroline Gale Denby and her partner stumbled upon the basement in their Crystal Palace apartment when they lifted a rotten floorboard and uncovered the 7-foot-high and 30-foot-long space.

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"We found it when taking up a rotten floorboard. It took a year [to do it all] because we did a lot of the digging ourselves," Denby told Newsweek.

The apartment is within a Victorian house, which would likely have originally had the box space below the floor to store coal.

Underground spaces like this were often linked to a coal chute between the early 19th and mid-20th century when coal was the primary form of home heating in major cities like London. Chutes would be used for delivery directly to an underground store below the home.

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In 1956, the Clean Air Act in the U.K. introduced "smoke control areas" in towns and cities in which only smokeless fuels could be burned. This forced a move toward oil and gas for home heating and many coal storage spaces and chutes fell into disuse.

Determined to make the most of the newfound space, Denby and her partner decided it would be used for more than storage. Instead, they aimed to create a more usable space.

"We wanted to make it a usable space, not just storage. Storage in London is hard to come by, but we wanted to make the space a bit special," Denby explained.

Pictures of the hidden basement area that the couple found underneath their London apartment. They decided they wanted to use the space for more than just storage. Pictures of the hidden basement area that the couple found underneath their London apartment. They decided they wanted to use the space for more than just storage. @carolinegaledenby/TikTok

The renovation process was far from easy. The couple spent numerous weekends living amid dust and debris. But despite the challenges, it soon paid off as they created a small but stylish cinema room.

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Denby shared a video of the find and new space on her TikTok page @carolinegaledenby where it has been viewed 48,000 times.

"That's fantastic!!!" said viewer Lynne. While TikToker LCP wrote: "Such a fab transformation!"

At the end of the video, the couple shared how they are using the newly renovated space that is now complete with a small heater, couch and projector for playing video games or watching TV.

"I wanted to share it because I wish I'd found someone with a similar experience! Coal chutes are common in Victorian houses, but are a small space," said Denby. "Space in London is precious—so we are just lucky we could do a lot of the labor ourselves at the expense of it taking a long time. But we love it."

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