The small village of Glencastle has some large mounds in the narrow valley that are not naturally occurring. They can be seen on the right hand side, close to the roadside on the approach to Belmullet from the east. These have never been archaeologically investigated but folklore legends recall that this was the old gateway into the Mullet and a toll had to be paid for each traveller who passed through or the traveller may never be seen again. There were no roads through this area of Mayo until less than two hundred years ago. In recent years the Glencastle Valley has been drastically altered by extensive quarrying.