How do you lose a town that once housed 10,000 people? Quite easily, it would seem. For hundreds of years, a bustling medieval town lay hidden in the British countryside, until an amateur archaeologist bought it on a hunch that ultimately proved correct. Now, 15 years after starting his excavations of the site on the English-Welsh border, Stuart Wilson has finally been vindicated by finding the Lost City of Trellech.

Archaeologists have been searching for the medieval town for a while, but had mistakenly been looking for it around the modern-day village of Trellech, in Wales. But back in 2002, Wilson, who was working in a toll booth at the time, was informed of a farmer on the English-Welsh border who had been finding bits of pottery in molehills, and thought that the subterranean mammals might be on to something.

After visiting the farm in question he found the remains of a wall. After taking a bit of a punt and buying the land when it next came up for sale for £32,000, his initially derided investment has now paid off. “People thought I was mad and really I should have bought a house rather than a field,” Wilson, who was in his early 20s at the time, told the Guardian. “But it turned out to be the best decision of my life. I don’t regret it at all.”

It has been a labor of love for Wilson to excavate the site over the last 15 years. But, with the help of over 1,000 volunteers, they have uncovered at least eight buildings, including the possible foundations of a moated manor house that is thought to have had two halls and a courtyard. As soon as the weather improves, Wilson plans to spend much of this season investigating this structure further.

During its heyday, the medieval town would not have been an insignificant settlement, with a population around a quarter of that of London during the same period. It is thought to have been founded by the De Clare family in the 13th century to manufacture weapons, armor, and other military equipment, and rapidly grew as it attracted local farmers and laborers to the urban center.

But the industrialized town crumbled after repeated attacks from the enemies of the De Clare family, and its position on the border made it the target for Welsh resistance against the English. Coupled with diseases that swept Trellech, and the town soon fell into ruin.

Wilson is now applying for permission to build a visitors center on the grounds, as well as a campsite to help encourage tourists to visit the dig and learn about its history.