When it comes to conducting renovations on older homes, there are no shortage of stories of unexpected finds behind walls or under floorboards. For one family in the U.K. countryside, what lay just a few feet under their property is now considered one of the most important historic discoveries in a decade.

Their remarkable story began last year with the decision to add electricity to a barn on the property in Wiltshire. While workers were digging the trench from the home to the barn to lay the cable, they found some perfectly preserved mosaic tiles.

Roman mosaic tiles The intricate mosaic tiles discovered during renovations tipped off archaeologists that something of great importance was buried under the property. (Photo: Luke Irwin/YouTube)

"To just have a member of the public turn up and say, 'I've found this mosaic,' and for it to be of such high quality, wonderful, top-notch fourth-century piece of workmanship is really rare," archaeologist David Roberts of Historic England said in a video. (Historic England is a public entity that looks after England's historic environment.)

As the researchers further examined the family's property, they began to uncover signs of something massive under the surface. A subsequent eight-day dig confirmed their suspicions that the site was home to an ancient Roman villa, the largest ever discovered in Britain, dating back more than 1,500 years.

You can see an artist's recreation of the villa in the video below:

"We believe that parts of the double-courtyard villa had three storeys, based on the very thick walls which survive to almost 1.5m high and 0.9m wide," Historic England shared in a news release. "These are capped with a base for a timber frame so we understand that the ground floor walls were built in large blocks, with a second storey of timber, topped with a stone tile roof."

In addition to a "perfectly preserved" Roman well, stone roof tiles, discarded oyster shells and other hints of the luxuries present at the villa, the researchers also discovered the stone coffin of a young Roman child. The family, unaware of the artifact's origins, had been using the stone coffin as a planter for geraniums.

ancient roman coffinc Previously used as a planter, this stone box was identified by researchers as the ancient coffin of a Roman child. (Photo: Luke Irwin/YouTube)

Roberts says Historic England is working with the owners to arrange for future excavations, but he admits that the most impressive aspects of the villa may have to remain hidden for now.

"The frustrating thing, of course, is that the mosaic is right under a gate leading to the modern buildings," he said, "Those modern buildings could be on top of who-knows-how-much more villa."

Owner Luke Irwin describes his experience in the video below: