This castle is situated on what is now known as the Island of Ross, on the east shore of Lough Lene, or the Lower Lake of Killarney, about a mile and three-quarters south of the town.

The island has been artificially formed by cutting across the peninsula or ros on which the fortress is built and from which it takes its name.

The channel, which is flooded by the waters of the lake, is crossed by a bridge, although it is usually dry during the summer months.

This bridge was formerly protected by a guard house and gates, which were closed every night, sentinels being posted at the entrance when the castle was garrisoned in later times.

The present ruins consist of a keep, with the remains of the surrounding bawn wall, which was flanked by semicircular towers at the corners. A spiral stone stair leads to the top of the keep, with doorways opening at the various floors.

The fortress is based on a limestone rock, and sustained on the land side by a buttress of masonry.

The peninsula contains 158 acres, and copper mines were opened on it in 1804, which were worked for four years, in which time £80,000 worth of ore was extracted. Water getting in stopped further work. It was clearly proved that the mines had been worked many centuries before, and a number of stone implements, locally called “Danes’ hammers,” have been found on the island.

The castle is supposed to have been built towards the close of the fourteenth century by the family of O’Donoghue-Ross, who added the appellation of their home to distinguish them from the family of O’Donoghue-More.

A modern barrack capable of holding some two hundred men and officers was erected against the keep, but when it ceased to be used Lord Kenmare had the unsightly erection removed.

There is a legend regarding a great and wise Prince O’Donoghue who possessed the secret of eternal youth, and under whose rule the land prospered greatly. It is related how that during a splendid feast at Ross Castle he rose up amongst the company and made a prophetic oration, recounting accurately all that the future years would bring. In the midst of speaking he walked over to a window (which is still shown) and through it he passed out over the lake. Upon nearing the centre he turned round and waved his hand in farewell to those behind, and, the waters opening, he disappeared beneath them.

On May morning he is said to rise from his watery grave and ride over the lake on a white steed, surrounded by beautiful women and youths. His appearance is looked upon as a sign of a bountiful harvest.

It is also related how a young maiden imagining herself in love with the phantom prince, cast herself into the lake on a May morning and was drowned.

The O’Donoghues were succeeded at Ross by the M’Carthy Mores, through whom the castle passed in 1588 to Sir Valentine Browne, ancestor to the present house of Kenmare.

In 1651 Lord Muskerry was guardian to his nephew Sir Valentine Browne, who was then a minor of about twelve years old. Hence it was that after his defeat by the Parliamentary forces at Knockniclashy on the 5th of July he retired with his army, numbering some one thousand five hundred men, to Ross.

Ludlow, accompanied by Lord Broghill and Sir Hardress Waller, followed with four thousand horse and two thousand foot.

Lord Muskerry was the last Royalist commander in arms, and his submission was a matter of great moment.

Ludlow reports that the castle was only accessible by the causeway which the besieged had fortified, being otherwise surrounded by water and bog.

Finding that this made the reduction of the fortress a matter of difficulty, and probably hearing of the tradition which stated Ross Castle could not fall until a ship should sail on the lake, Ludlow asked for a small fleet of boats to be prepared for transport at Kinsale.

In the meantime he found that the besieged were obtaining supplies through the thick woods surrounding the island. A force of two thousand foot were, therefore, despatched to clear the thickets. Some of the enemy were killed, some taken prisoners, and the rest saved themselves “by their good footmanship.”

The rest of Ludlow’s forces were employed in fortifying the peninsular so that a few men could keep the besieged in, while a large company was despatched to Killorgan, on Castlemain Bay, to receive the boats and supplies.

The preparation for the expedition was undertaken by the Rev. Dr. Jones, and the command was given to Captain Chudleigh.

The vessels were sent in pieces, so that the workmen who accompanied them could put them together in a few days. Two pinnaces carrying ordnance, and capable of holding fifty (or Ludlow says a hundred and fifty) men, were forwarded so as to be ready for use in two days. Also five or six boats to hold fifty men each, and material to make more.

Great has been the controversy as to what route was followed in conveying these vessels to Killarney. The River Laune, which drains the lakes, is not navigable above the place where Ludlow’s force was to receive the goods.

Tradition asserts that they were conveyed by the mountain road, and in Ware’s Annals it is recorded that a ship was “carried over the mountains.” On the other hand, Smith distinctly says they were “brought up by the River Lane, by strength of men’s hands.” He also relates how a recent sexton of Swords, called Hopkins (who had died at the age of 115), had been one of those who “assisted in drawing the above-mentioned vessel into the lake.” It is, therefore, likely that Smith’s informant on the matter had received the correct impression from an eye witness.

On Captain Chudleigh’s tomb at St. Multon’s, Kinsale, the fact is recorded of his having constructed a ship to sail on land for the reduction of Ross.

Some naval men are said to have drawn a vessel up the Laune in later years.

It is on the whole most likely that the hulls of the pinnaces were brought up by the river bed, while the lighter craft were conveyed by road. At any rate the transport and preparation occupied only the short period of four days, at the end of which time the terrified garrison perceived a warship being rowed upon the lake.

It is not unlikely that pressure was put on Lord Muskerry by his superstitious garrison, for no sooner had the vessel appeared than he notified to Ludlow that he was willing to treat.

Commissioners were appointed on both sides, and after a fortnight spent in debating the terms the treaty of Ross was signed. Lord Muskerry’s son and Sir Daniel O’Brien were delivered as hostages.

Fair terms were granted to the Royalist Army, and five thousand horse and foot laid down their arms.

For a long time Ross Castle gave rank and emolument to a governor. One of these owed his position to the confusion of names between New Ross, County Wexford, and the Ross of Killarney, for having rendered valuable service at the former during the rebellion of 1798, the governorship of the latter becoming vacant he was at once appointed.