Muiredach’s High Cross is one of three surviving high crosses located at Monasterboice (Gaeilge: Mainistir Bhuithe, “Buithe’s monastery”). The monastic site is said to be founded in the 6th century, by St. Buithe. It is most famous for its 9th and 10th century high crosses—most notably Muiredach’s High Cross. These crosses are all made of sandstone and are referred to as the North, West, and South Crosses. It is not certain whether they stand in their original locations. The South Cross is commonly known as Muiredach’s cross because of an inscription on the bottom of the west-face. The inscription reads ÓR DO MUIREDACH LAS NDERNAD IN CHROS, which translates from Gaeilge as “a prayer for Muiredach who had this cross made”. It is thought that this Muiredach is likely Muiredach mac Domhnall (died 923), who was one of the monastery’s most celebrated abbots; he was also the abbot-elect of Armagh and also the steward of the southern Uí Néill. There is, however, another abbot named Muiredach who died in 844. Another possibility is that Muiredach may refer to Muiredach mac Cathail (died 867); a king whose territory included the site of the monastery.
The cross measures about 19 feet (5.8 m) high; including the base, which measures 2 feet 3 inches (0.69 m). The cross is made of sandstone which is yellow in colour. The main shaft of the cross is carved from a single block of sandstone; the base and the capstone on the top are carved from separate stones. The base is the shape of a truncated pyramid of four sides. It measures 2 feet 2 inches (0.66 m) high and 4 feet 9 inches (1.45 m) at the bottom; it tapers to 3 feet 8 inches (1.12 m) by 3 feet 4 inches (1.02 m) at the top. The main shaft is rectangular, measuring 6 feet 6 inches (1.98 m) high; 2 feet 2 inches (0.66 m) by 1 foot 8 inches (0.51 m) at the bottom. tapering to 2 feet 4 inches (0.71 m) by 1 foot 7 inches (0.48 m) at the top. The topmost stone, or capstone, is carved in the shape of a house, with a sloping roof; and has a crescent-shaped finial at each end. It is thought that such house-shaped capstones may represent reliquaries, which, like the Monymusk Reliquary, typically took this form in Celtic Christianity.
Every piece of the cross is divided into panels which are decorated with carvings. The carvings are remarkably well preserved; however, they certainly would have originally had much finer detail. Even so, certain details about clothing, weapons, and other things, can still be clearly made out. Biblical themes dominate the carved panels; though there are pieces which feature certain geometric shapes and interlace ornaments.
XXth century Irish archaeologist Robert Alexander Stewart Macalister noted that there are 124 figures sculpted upon the panels of the cross—119 of which shown in some form of costume. The cross is not unlike other works of Insular art where the artist has represented people in contemporary costume. All, except one, of the figures is depicted bare-headed. The lone figure with headgear is Goliath, who wears a conical helmet. Generally the hair is worn clipped in a straight line over the forehead, though in some cases it is shown to be distinctly curly. Many of the figures have no facial hair, though several of them wear very long moustaches, with heavy ends which hang down to the level of the chin. There are very few beards represented; those shown with beards are Adam, Cain, Moses and Saul. Macalister considered that the artist excelled in the geometric and abstract patterns which appear on the cross. On the ring surrounding the head of the cross, there are 17 different patterns. Macalister stated that Celtic geometric patterns fall into three categories: spiral, interlace, and key-patterns.