Antrim, a county in the province of Ulster, Ireland, bounded north and east by the sea, south by Belfast Lough and the river Lagan, west by Lough Neagh and the counties Down and Londonderry. It is about 54 miles long by 28 broad, and has an area of 1,191 square miles. Towards the east bogs and mountains prevail, rendering some 120,000 acres sterile, but about two-thirds of the soil is arable. The prosperity of the county depends, however, on the manufacture of linens, which is carried on at Belfast, Lisburn, Larne, Ballymena, Ballymoney, Carrickfergus, and Antrim. There are large ironworks, too, and the fisheries are good, whilst the inland districts supply large quantities of butter. The masses of columnar basalt, known as The Giants' Causeway, form a remarkable natural feature, and the county is rich in Celtic antiquities. The inhabitants are mainly Protestant colonists from England and Scotland. Antrim town is at the north extremity of Lough Neagh, 13 miles northwest of Belfast.