[1] The north hilltop (of three peaks) is surrounded by over 5 km (3.1 mi) of ramparts, enclosing an area of about 16 ha (40 acres) in which at least 300 level platforms have been cut into the rock to provide bases for turf or timber-walled houses, forming one of the largest hill forts known in Scotland.

[2] In the 1st century AD the Roman army built the massive fort of Trimontium at Newstead, named after the three peaks, at the foot of the hill on the bank of the River Tweed.

In association with this fort they constructed a signal tower with a tiled roof in a 15 m diameter enclosure built on the summit of Eildon North Hill.

Sir Walter Scott tells the tale of a horse dealer who is paid in "ancient coin" by an elderly buyer in old-fashioned dress and taken inside the hill at night.

A host of armed knights lie asleep at their horses' feet; their sleeping leader is King Arthur.

[14][15] Another legend concerns the Eildon Tree Stone, a large moss-covered boulder near Melrose, marking the spot where the Fairy Queen led Thomas into her realms in the heart of the hills.

[12] The volcanic rock was said to have been cleft in three by the wizard Michael Scot, as relayed by Walter Scott in his 1805 poem, The Lay of the Last Minstrel: In these far climes it was my lotTo meet the wondrous Michael Scott,A wizard, of such dreaded fame, Than when, in Salmanca's cave,Him listed his magic wand to wave,The bells would ring in Notre Dame!Some of his skill he taught to me;And Warrior, I could say to theeThe words that cleft Eildon hills in three,And bridled the Tweed with a curb of stone:But to speak them were a deadly sin.James Hogg retold the legend in his 1823 novel The Three Perils of Man.