The National Trust for Scotland is appealing to the public to report any sightings of mysterious structures hidden in remote glens so they can be properly catalogued, reports iNews. There is a chance the site could have been used to house a still.

Thousands of illicit stills were once in existence in hidden areas of the Scottish Highlands, but only around 130 sites have been discovered and entered onto Scotland’s database of archaeological sites.

While whisky has been taxed in Scotland in some form since the Excise Act of 1644, small scale private production was exempt. However, within a hundred years these private distillers were producing around 500,000 gallons of whisky a year, depriving the Crown of its duty. In 1781 making whisky for private consumption was banned.

Many of these stills kept producing whisky, only now having to go underground and away from the prying eyes of tax collectors or law enforcement officials. The ban did not affect production too badly, it was estimated in 1787 300,000 gallons of whisky were smuggled across the border into England.

According to the NTS, the difficulty from an archaeological point of view is trying to tell it a site was used for whisky or for general agricultural. The sites needed to be close to a water supply and peat, along with be close to a path or road.

PHOTOS: NTS