In Irish mythology, Naisi, Noíse or Noisiu was the nephew of King Conchobar mac Nessa of Ulster, and a son of Uisneach. He is mentioned in the tale known as the Tragic Tale of the Sons of Uisnech, or Exiles of the Sons of Uisnech, usually found within the set of stories in the Táin Bó Cúailnge, part of the Ulster Cycle.

Navan Fort is an ancient ceremonial monument near Armagh, Northern Ireland. According to tradition it was one of the great royal sites of pre-Christian Gaelic Ireland and the capital of the Ulaidh. It is a large circular hilltop enclosure—marked by a bank and ditch—inside which is a circular mound and the remains of a ring barrow. Archeological investigations show that there were once buildings on the site, including a huge roundhouse-like structure that has been likened to a temple. In a ritual act, this timber structure was filled with stones, deliberately burnt down and then covered with earth to create the mound which stands today. It is believed that Navan was a pagan ceremonial site and was regarded as a sacred space. It features prominently in Irish mythology, especially in the tales of the Ulster Cycle. According to the Oxford Dictionary of Celtic Mythology, "the [Eamhain Mhacha] of myth and legend is a far grander and mysterious place than archeological excavation supports".