Harboro' Rocks are an impressive outcrop of dolomitic limestone.
At the top of the rocks between the trig point and the rock 'chair' there used to be a chambered cairn, now sadly destroyed. Altho' inspecting the ground shows what maybe traces of a rim. The cairn was thought to date to the Neolithic, and several crouched skeletons were found in the chamber.
In the early Iron age the site was used, and some bumps in the terraces on the eastern side are thought to be housing platforms.
Access is easy, there's room to park near the Hopton Works.
The views from the top have got to be seen, and there's a few strange shaped natural menhirs dotted around the place. And caves to explore on the lower terraces.
This is a summary of an article printed in Archaeologia volume 9.
Mr. Rooke is the author of the next article, which informs us of druidical remains on Harborough Rocks, Derbyshire; viz. circles, caves, basons, &c. The most remarkable is a rock cut in the shape of a great chair, near another stone having a bason at the top. One of these huge rock-chairs is situated at the side of a small plain opposite to a rock-idol. They are supposed to have been the occasional seats of the officiating druids; who, being near the rock bason, might conveniently consult the pure water, or snow, collected in it.
From p9 of the Monthly Review v2, 1790 (which is online at Google Books). Pretty much says what Stubob says! but 200 years before.
In the 1920s at least, the cave on the south west face was "known locally as the Giant's Cave".
so says p204 of 'Exploration of Harborough Cave, Brassington.'
A. Leslie Armstrong
The Journal of the Royal Anthropological Institute of Great Britain and Ireland, Vol. 53. (Jul. - Dec., 1923), pp. 402-413.
..We asked the woman some questions about the tomb of the giant upon the rock or mountain: She told us, there was a broad flat stone of a great size lay there, which, she said, the people call'd a gravestone; and, if it was, it might well be called a giant's, for she thought no ordinary man was ever so tall, and she describ'd it to us as well as she could, by which it must be at least sixteen or seventeen foot long; but she could not give any farther account of it, neither did she seem to lay any stress upon the tale of a giant being buried there, but said, if her husband had been at home he might have shown it to us. I snatched at the word, at home! says I, good wife, why, where do you live. Here, sir, says she, and points to the hole in the rock. Here! says I; and do all these children live here too? Yes, sir, says she, they were all born here. Pray how long have you dwelt here then? said I. My husband was born here, said she, and his father before him..
..On one side was the chimney, and the man, or perhaps his father, being miners, had found means to work a shaft or funnel through the rock to carry the smoke out at the top, where the giant's tombstone was. The habitation was poor, 'tis true, but things within did not look so like misery as I expected. Every thing was clean and neat, tho' mean and ordinary: There were shelves with earthen ware, and some pewter and brass. There was, which I observed in particular, a whole flitch or side of bacon hanging up in the chimney, and by it a good piece of another. There was a sow and pigs running about at the door, and a little lean cow feeding upon a green place just before the door, and the little enclosed piece of ground I mentioned, was growing with good barley; it being then near harvest..
The cave has been excavated several times. Finds included 2 human burials, dated to the Neolithic/Bronze Age.
Neolithic, Bronze Age and Iron Age pottery, leaf shaped arrowheads, flint and chert artefacts.