The first accurate account of population is in the 1801 census which records 138 residents. We are indebted to the Romans for planning their main thoroughfare between Caerleon and Caerwent to pass through what is now the A48 in Penhow.
The name Penhow is derived from the welsh word Pen (Hill) and How derived from ‘Haugr’ Old Norse, apparently related to the Old Teutonic word ‘Huagh’ meaning Hill, Cairn or Mound.
Penhow is known for Penhow Castle, which has claims to be the oldest inhabited castle in Wales. It was built as a home for Sir Roger de Sancto Mauro, one of the Norman knights who served the Norman Lord of Striguil at Chepstow Castle. He built a tower house, and documentary evidence shows that he was at Penhow by 1129.
It was the first British home of the family who would later rise to national prominence under the more familiar name of Seymour. Later the Seymour family sold Penhow Castle to the Lewis family of St. Pierre, who converted the castle to a modern residence in 1674. Thomas Lewis’ son Thomas was High Sheriff of the county, and married the daughter of Sir Richard Levett, Lord Mayor of London. The Lewis’ retained ownership of Penhow Castle for several centuries. The castle has a reputation for being haunted. It was open to the public between 1978 and 2002.
Church of St. Johns the Baptist
The parish church of St. John the Baptist is next to the castle. The original Church tower could be the same date as the early parts of the Castle, and was completed in 1290 and dedicated to the Abbot of St. Maur in France, the home of the St. Maur (Seymour) family. Following the reformation the Church was rededicated to St. John the Baptist.
Penhow also holds the current record July temperature for Wales, 34.2°C (93.5°F) set on July 19, 2006.