Believed to have been the royal and religious capital of Ulster from 1150 B.C. until the spread of Christianity, the Navan Fort is a mysterious place. Its central circular earthwork enclosure holds a smaller circular structure, and it all encloses an Iron Age burial mound. Even today, scientists do not really know what it was used for, although they know that it was all set on fire around 95 B.C., possibly as part of a ritual. Unfortunately, the extremely useful interpretive center at the site is sometimes closed due to lack of funding. However, if you happen to catch it open, it's an excellent resource with exhibits and multimedia presentations to explain the history and prehistory of the site. A book, gift shop, and cafe are also on hand.