A mountain top with an Iron Age hillfort and Bronze Age burial cairns. There is a load of lore associated with the area but Wirt Sikes relates a great tale with fairies in his British Goblins:
It is now about fifty years ago since a stripling, of twelve or more years of age, was tending his father's sheep on a small mountain, called Frennifach; it was a fine morning in June, and he had just driven the sheep to their pasture for the day, when he looked at the top of Frennifaur to observe which way the morning fog declined, that he might be judge of the weather (*if the fog on Frennifawr declines to the Pembrokeshire side, the peasants prognosticate fair; if on the Cardigan side, foul weather), and to his surprise, saw what seemed a party of soldiers sedulously engaged in some urgent affair; knowing there could not possibly be soldiers there so early, he, with some alarm, looked more minutely, and perceived they were too diminutive for men; yet thinking his eyesight had deceived him, he went to a more elevated situation, and discovered that they were the Tylwyth Teg dancing.
He had often heard of them, and had seen their rings in the neighbourhood, but not till then had the pleasure of seeing them; he once thought of running home to acquaint his parents, but judging they would be gone before he returned, and he be charged with a falsehood, he resolved to go up to them, for he had been informed that the fairies were very harmless, and would only injure those who attempted to discover their habitations; so by degrees he arrived within a short distance of the ring, where he remained some time observing their motions.
They were of both sexes, and he described them as being the most handsome people he had ever seen, they also appeared enchantingly cheerful, as if inviting him to enter and join the dance. -- They did not all dance, but those who did, never deviated from the circle; some ran after one another with surprising swiftness, and others (females) rode on small white horses of the most beautiful form. Their dresses, although indescribably elegant, and surpassing the sun in radiance, varied in colour, some being white, others scarlet, and the males wore a red tripled cap, but the females some light head dress, which waved fantastically with the slightest breeze.
He had not remained long ere they made signs for him to enter, and he gradually drew nearer till at length he ventured to place one foot in the circle, which he had no sooner done than his ears were charmed with the most melodious music, which moved him, in the transport of the moment, to enter altogether: he was no sooner in, than he found himself in a most elegant palace, glittering with gold and pearls; here he enjoyed every variety of pleasure, and had the liberty to range wherever he pleased, accompanied by kind attendants beautiful as the Houries; and instead of Tatws llaeth, buttermilk, or fresh boiled flummery, here were the choicest viands and the purest wine in abundance, brought in golden goblets inlaid with gems, sometimes by invisible agency, and at other times by the most beautiful virgins.
He had only one restriction, and that was not to drink, upon any consideration (or it was told him it would be fatal to his happiness), from a certain well in the middle of the garden, which contained golden fishes and others of various colours. New objects daily attracted his attention, and new faces presented themselves to his view, surpassing, if possible, those he had seen before; new pastimes also were continually invented to charm him, but one day his hopes were blasted, and all his happiness fled in an instant. Possessing that innate curiosity common to most of us, he, like our first parents, transgressed, and plunged his hand into the well, when, the fishes instantly disappeared, and, putting the water in his mouth, he heard a confused shriek run through the garden: in an instant after, the palace and all vanished away, and, to his horror, he found himself in the very place where he had first entered the ring; and the scenes around, with the same sheep grazing, were just as he had left them.
He could scarcely believe himself, and hoped, and hoped again, that he was in the magnificent fairy castle; he looked around, but the scene was too well known: his senses soon returned to their proper action, and his memory proved that, although he thought he had been absent so many years, he had been only so many minutes.