From Atlas and Cyclopedia of Ireland (1900)
NAME.—County named from the city. The most ancient name of Londonderry was Derry Calgagh, i.e., the derry or oak-wood of Calgach. In veneration for St. Columkille, who erected his monastery in Derry in 546, it began in the 10th or 11th century to be called Derry Columkille; and this continued to the time of James I., whose charter, granted to a company of London merchants, imposed the name Londonderry.
SIZE AND POPULATION.—Length from Magilligan Point to the Ballinderry River, 40 ½ miles; breadth from the southwestern corner beside the Foyle, to the northwestern boundary near Coleraine, 35 miles; area 816 square miles; population 164,991.
SURFACE.—A belt of level land stretches more than half round the county from Lough Neagh, by Colerain to the Foyle, six or seven miles broad along the Bann, but much narrower along Lough Foyle. There is a large tract of beautiful level country in the center; and the south of the county is mountainous, the southern border, where it verges on Tyrone, remarkably so—an almost uninterrupted mass of high mountains.
MOUNTAINS AND HILLS.—In the southwest, the Sperrin Mountains run in a curve from near Strabane in Tyrone to near Garvagh in this county, lying partly in Tyrone, partly on the border between Tyrone and Londonderry, and partly in Londonderry. The chief summits touching or belonging to Londonderry are Sawel (2,240); a mile to the southwest of it, Dart (2,040); Meenard (2,061), 3 miles from Sawel, nearly due east, and Oughtmore (1,878) 2 miles east of Meenard—these four being on the boundary with Tyrone. The following are in Londonderry: Barnes Top (1,506) and Mullaghash (1,581), northwest of Meenard; and as you go northeast from this, Craigagh (1,489), near Oughtmore; Mullaghmore (1,825), White Mountain (1,774), Brown Hill (1,278), and Streeve (1,282), all four close to each other; Glenshane Mountain (1,507), and Craigmore (1,306).
South of these, and west of Draperstown, are Knockbrack (1,735), and on the boundary Slieveavaddy (1,605) and Mullaghturk (1,353); all these belonging to a range separated from the Sperrin Mountains by the valley of Glenelly River.
Toward the southeastern corner of the county stands the short range of Slieve Gallion (1,623), separated from the Sperrin Mountains by the valley of the Moyola River. Five miles south of Londonderry city is Slievekirk (1,219), on the boundary with Tyrone.
The following are in the interior: Benbradagh (1,536), northeast of Dungiven; north of this, Craiggore (1,277), Boyd's Mountain (1,077) and Keady Mountain (1,101), near Newton Limavady; and north of the same town, about half way toward Magilligan Point, Binevenagh (1,260), almost detached, and commanding a beautiful view on all sides. Loughermore (1,298) lies southwest of Limavady; and northwest from Sawe are Meeny Hilll (1,198) and Straid Hill (1,002).
COAST LINE.—That part of the coast lying between Portrush and the mouth of the Bann is bold, rocky, and cliffy. From the mouth of the Bann, round by Magilligan, the strand is flat and sandy; but a mile or two inland there are fine cliffs and hills, culminating in Binevenagh. From Bellarena west to the Foyle, both shore and interior are flat, but well cultivated and very beautiful. The only cape of any consequence is Magilligan Point, a sandy projection, confining on the east the entrance to Lough Foyle.
RIVERS.—The Bann, issuing from Lough Neagh, runs on the boundary between Antrim and Londonderry for a mile, then after flowing through Antrim for half a mile, it expands into Lough Beg: issuing from Lough Beg, it again forms the boundary for 22 miles down to Colebreene; and from that to the mouth, a distance of 10 miles, it flows through Londonderry. A mile above Coleraine it falls over a ledge of rocks, forming the "Salmon Leap" cascade, where there is a great salmon fishery. On the west side, the Foyle flows through this county for the last 11 miles of its course.
The Faughan rises at the base of Sawel Mountain, and running northwest, flows into the mouth of the Foyle. The Faughan receives as tributaries, on the left bank, the Glenrandal, which rises in Tyrone, and the Berry Burn, rising in Slievekirk; and on the right bank the Burn Toilet. The Roe rises on the southern boundary at a great height among the Sperrin Mountains, and flowing in a general direction northward, it passes by Dungiven and Newton Limavady, and enters Lough Foyle.
The Moyola flows from the mountains in the southwest border, and running first northeast, next east, and lastly southeast, it enters the northwest corner of Lough Neagh. Like the Roe, it rises at a great elevation, and is subject to sudden floods. Its tributaries are: on the right bank, the White Water and the Grange Water; on the left bank, the Glengomna and the Douglas. South of this, the Ballinderry River forms the boundary with Tyrone for the last 8 or 10 miles of its course, and enters Lough Neagh; a little higher up it also runs on the same boundary for a mile and a half. It receives the Lissan Stream on the left bank, which flows partly on the boundary with Tyrone, but chiefly through Londonderry. The Londonderry tributaries of the Bann, north of the Moyola, are the following: The Claudy flows east and joins the Bann half a mile below Portglenone, receiving as tributaries on its left bank the Grilagh and the Knockoneill River. Below this is the Inverroe Water; next the Agivey River, which is joined on the left bank by the Aghadowey River and by the Mettican River; and lastly the Macosquin River.
LAKES.—Lough Neagh forms the boundary for 8 miles, and Lough Beg for 3 ½ miles. In the southwest, Lough Fea and the mountain pool Lough Ouske lie on the boundary with Tyrone.
TOWNS.—Londonderry (29,162,) the assize town, built on a hill rising over the left or western shore of the Foyle, is a most picturesque city, rendered highly interesting by its remains of antiquity, especially the old walls, gates, and bastions that formerly defended the town. On the eastern side of the county is Coleraine (5,899), on the Bann, 4 miles from its mouth. Higher up, Kilrea (935) is half a mile from the river.
On the Roe are, Newtown Limavady (2,954); and Dungiven (761), in a beautiful valley, with the ruins of a castle and of a very ancient abbey. Magherafelt (1,514) stands in the southeast, 4 miles from the shore of Lough Neagh; near it, on the Moyola River, is Castledawson (511); a little higher up, near but not quite on the same river, Tobermore (347); and higher up still, Draperstown, half a mile from the river. Maghera (1,124), a little to the north of the Moyola, is a place of great antiquity, with a most interesting and very ancient church ruin; Garvagh (708) is farther north, 4 miles from the Bann; Moneymore (588), in the southeastern corner, is a very neat town; and on the north coast, Port Stewart (556) is a pretty watering place, and much patronized.
ANCIENT DIVISIONS AND DESIGNATIONS.—-Londonderry formed a part of the ancient territory of Tir Owen, i.e., the land of Owen, son of Niall of the Nine Hostages. The barony of Keenaght represents the ancient territory of Cianachta, or Cianachta of Glengiven, which was in early times the territory of the O'Conors; but they were dispossessed a short time before the English invasion by the O'Cahans or O'Kanes.
One mile above Coleraine, towering over the right bank of the river, is a great fort or mound, one of the largest in the country, now called Mountsandel, but anciently Dun-da-bheann (pron. Dundavan'), or the fort of the two peaks or gables, which was the residence of a chief called "Niall of the brilliant deeds" a little before the Christian era, and which is celebrated in ancient Irish romance. A still more celebrated fort lay about 5 miles west of this in the parish of Dundo; it is now called the Giant's Sconce, but it was the ancient Dun Kehern, the residence of Kehern, one of the Red Branch Knights. (See Armagh.)
In Roe Park, near Newtown Limavady, is a long mound now called "the Mullah" or "Daisy Hill;" this is the ancient Drumket, celebrated for the convention held there 574 by Aed, the son of Ainmirè, king of Ireland, which was attended by the chief people of the country, both lay and ecclesiastical, among others by St. Columkille, and in which various important national matters were settled.