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. The excellent interpretive center puts it all into context, complete with exhibition and reconstructed Iron Age houses. Admission rates are discounted slightly in the winter months.