[2] Longtown is located 10 miles (16 km) north east of Abergavenny and 14 miles (23 km) south west of Hereford on the eastern edge of the Black Mountains, Wales, part of the Brecon Beacons National Park.

There are numerous footpaths and bridleways on the mountains, and they include Offa's Dyke Path, which runs north-south along the top of the Hatterall ridge.

Longtown has an early Norman motte and bailey castle, Longtown Castle, and is so named because the settlement today is strung out along the lowland / winter road connecting Hay-on-Wye with the Abergavenny to Hereford road.

The township or civil parish of Longtown includes the hamlet of Clodock.

Longtown Mountain Rescue based in nearby Abergavenny originated from staff of the Longtown Outdoor Centre in 1965 and are still ready to rescue people in difficulties on the upland ridges or lonely valleys of the Black Mountains in all seasons, such as the Hatterall Ridge to the west and the Black Hill (Herefordshire) to the north.