A couple renovating a 19th-century church in upstate New York have captivated millions online after discovering something unusual: two exterior windows that appear to belong to a room that doesn't exist.

Lauren Gunderman, 31, told Newsweek she and her partner are transforming the 1872 church into a luxury wedding and events venue.

The owners of The Stately on Main, a former Presbyterian church in Waterville, have been documenting their search for what they believe is a hidden space concealed somewhere inside the building.

Gunderman and her partner's investigation has sparked widespread fascination online, with viewers offering theories, warnings and even expert analysis in an effort to solve the mystery.

In a video shared on Instagram on May 25 by @127eastmain, the couple are seen trying to break into what they describe as a "mystery room" inside the church.

The clip shows the pair focusing on a suspected entry point in the ceiling, where wooden boards had been placed beneath the area they believed the hidden room might be located. They begin pulling the boards away, hoping to uncover access.

"How the hell we get into this mystery room?" the poster asks in the video.

The search began when the couple noticed two exterior windows that didn't appear to correspond with any visible interior space. Convinced there had to be a hidden room somewhere inside the church, they started hunting for a way in.

At one stage they discovered a small opening beneath the area where they believed the room should be located. The gap had been boarded over, raising hopes they had finally found an entrance.

But after removing the boards and even lowering a phone into the space to investigate, the couple found only more structure and no sign of a hidden room.

"Another attempt at getting into the mystery room in my 1872 church! Why am I wearing pink slides with socks?" the caption reads.

"In this video, we're trying to locate the ‘mystery room,’ which is wherever those two windows you see on the exterior actually exist inside the church. We figured going through the floor would get us there, but instead we just found…more floor," Gunderman said.

Although the room has not been accessed, she added that viewers may have already helped solve the mystery.

"Spoiler: after receiving a flood of comments from organ experts, I've since learned the windows were likely boarded up inside the organ room after it was electrified but I don't want to mess with the pipes, so we may never know for sure!" Gunderman said.

The video quickly gained traction online, drawing more than 4.9 million views and over 137,000 likes, as viewers became invested in the search.

One user, Jk_its_me_scarlett, commented: "So you bought an old church with a boarded off room…. and your first thought was how do we get in there? That’s where the demon sleep."

Oscar.a.mejia said: "Old church, boarded up room, yep I’m not opening that up!"

Starcatcher1966 added: "So, wait you bought and old church, found a closed off, completely closed off sealed off room or space and your first thought is how do I get in?? Nope nope nope…have it blessed and hope whatever they boarded up/sealed in there stays in there."

Do you have funny and adorable videos or pictures you want to share? Send them to life@newsweek.com with some extra details and they could appear on our website.