Finavon Hillfort

Vitrified Fort at Finavon.
[...] There is a popular legend to the effect that the remains of the fort are the ruin of the first castle which it was attempted to build at Finavon. The attempt was not allowed to proceed far; not further than the laying of the foundation. Anything more which the builders raised during the day was always knocked down by some demon-power in the course of the next night.

Watchers were set to protect the work, and to frighten away the mischievous spirit; but the result was that the watchers themselves were frightened. At midnight the spirit spoke thus to the watchers amidst the din of the tumbling wall built the previous day: -

Found even down into the bog
Where twill neither shake nor shog.

They took the hint and left the hill.