Emain Macha (said roughly like evan macka) features largely in Irish mythology, though it's far more likely you'll find it on maps or referred to by it's English name, Navan Fort. Technically, it isn't a fort. It is instead best described as a ritual complex, about 1.6 miles west of the city of Armagh, in Northern Ireland.

The complex sits on a low mound, and is visible quite clearly for some distance. The site was largely abandoned by the first century C.E. The central area is a circular area about 820 feet in diameter, set off by a raised bank and a ditch, with the ditch atypically outside the bank—this suggests that the site was used for ritual rather than defensive purposes. There are two sets of ruins inside the enclosed area; an earthen mound, about 130 feet in diameter, and about 20 feet high lies to the north-west; this is generally what most people think of when they hear Emain Macha. To the south-east is what's left of a a ring-barrow, the remains of a late prehistoric ritual area, and burial mound.

The mound was likely constructed c. 95 B.C.E.—a date that's extraordinarily reliable because it's based on dendrochronology. When it was first built, the site consisted of four rings of posts, arranged concentrically around an immense central oak post or trunk. The entrance faced west, towards the sunset instead of the common domestic entrances of structures from the same era which typically face the east. Inside the floor was tamped down and covered with lime stone blocks brought from elsewhere and carefully arranged in radial patterns from the center out, to a height of about three meters. There may have been a roof, originally. The entire structure was deliberately burned down shortly after it was built, then carefully covered in an mound of dirt, which in turn was covered with turf. This is a pattern that archaeologists have noticed at two other ritual sites, Tara, and Duún Ailinne.

The remains of the ring-barrow are harder to date. Non-invasive geophysical surveys have determined that beneath the surface lies a figure-eight shaped wooden structure, with one ring of the figure larger than the other. The site appears to have been used for generations, with the central sites rebuilt at least twice. Beneath them are still older sites, smaller, each with its own central hearth. Artifacts found at this level during a dig in the 1980s include pottery fragments, bones, and other items that indicate that they were inhabited in the last centuries of the Bronze age, and into the early Iron age, or from roughly 600 to 250 B.C.E.

An even earlier circular ditch surrounds the mound, though it's not readily visible; it's an early Bronze age structure, and limited excavations found flint tools and pottery shards indicative of Neolithic era activity at the site, c. 4000 to 2500 B.C.E. Nearby, about two-thirds of a mile to the west is Haughey's Fort, an early Bronze Age hill fort, and The King's Stables, a man-made pool from the Bronze age, both of which pre-date the structure at Emain Macha. In addition, Loughnashade, a natural lake and source of a number of fine Iron Age artifacts, is nearby.

There are three closely related "origin myths" regarding Emain Macha. All of them revolve around a woman named Macha. The woman named Macha appeared one day, and without a word, began to care for Crunncu Mac Agnomain, a man of Ulster. But because of his boasting regarding her ability to run, Macha was forced to race against two of the king's horses, even though she asked for mercy given her advanced pregnancy. Macha died giving birth to a son and a daughter at a single birth at the finish-line. Thus it is said that Emain Macha is named for the twins, emain, of Macha.

Another tale has the name Emain Macha from this. Three Ulster kings, Dithorbae, Aed the Red, and Cimbaeth shared the kingship, each ruling for a seven years then another taking his place in turn. Each man reigned three terms, that is sixty-six years. Aed the Red died at the beginning, and he left only a daughter. Her name was Macha the Red-haired.

Macha demanded the kingship in her proper turn. Cimbaeth and Dithorbae said they would not give kingship to a woman. Macha vanquished them in battle, and ruled seven years. Dithorbae died in Corann during that time, and left five sons, who demanded the kingship. Macha said she would not give it to them, "for not by agreement did I take it," said she, "but by force in the field of battle." Macha vanquished the sons of Dithorbae in battle, and they fled in exile to the wilderness of Connacht. Macha then took Cimbaeth for her husband.

After Macha and Cimbath were united, Macha went seeking for the sons of Dithorbai, disguised as a leper woman. She found them in Connacht cooking a wild boar. The men asked for news from her, and she told the news to them and they gave food to her at the fire. One of the brothers said "the eye of this hag is beautiful, let us lie with her." The brother took Macha into the forest, where she bound him by means of her strength and left him in the wood. When she came back to the fire, the others asked "Where is the man who went with you?"

"He was ashamed to come to you," said Macha, "after lying with a leper woman."

"It is no shame," said they, "for we will all do the same."

Each man took Macha into the wood, where she bound each of them in turn, taking them in a single chain with her to Ulster. The Ulsterman said the men should be killed. "No," said Macha, "for to kill them would be a violation of true justice from me as ruler; but I shall put them under bondage, and they shall dig a rath [a ring-fort] for me that will be the chief town of Ulster for ever."

And Macha took the gold pin from about her neck and marked out the lines of the fort with it, thus Emain Macha is named for the gold pin about the neck [muin] of Macha.

You can decide for yourself which origin myth you prefer, but you should be sure to visit Emain Macha. Navan Centre, the official gateway to Emain Macha or Navan Fort is a bit of a tourist trap of the "experience authentic Ireland" variety, but Emain Macha and the associated sites are very much worth the visit, and the more fanciful parts of the Centre can be easily avoided. That said, the Centre is temporarily closed (the site is still open) for renovations until July of 2009.