Armagh is the county town of County Armagh in Northern Ireland. It is the ecclesiastical capital of Ireland – the seat of the Archbishops of Armagh, the Primates of All Ireland for both the Roman Catholic Church and the Church of Ireland. In ancient times, it and nearby Navan Fort (Eamhain Mhacha) was one of the great royal capitals of pagan Gaelic Ireland. Today it is home to two cathedrals and the Armagh Observatory.
The cache is a magnetic nano and parking is beside it on the roadside. Take care with passing traffic and some stealth is required. So as you don't have to dwell too long on this busy road, the hint is obvious.
Stealth will be required here.