Abergavenny (/ˌæbərɡəˈvɛni/; Welsh: Y Fenni, pronounced [ə ˈvɛnɪ], archaically Abergafenni, 'mouth of the River Gavenny') is a market town and community in Monmouthshire, Wales.

Abergavenny provides access to the nearby Black Mountains and the wider Brecon Beacons National Park.

In the UK 2011 census, the six relevant wards (Lansdown, Grofield, Castle, Croesonen, Cantref and Priory) collectively listed Abergavenny's population as 12,515.

The ground rises gradually in the north of the town before steepening to form the Deri and Rholben spurs of Sugar Loaf.

The high ground at either side is formed by a legacy of the last ice age, the recessional Llanfoist moraine which underlies both the village which gives it its name, the town centre and the Nevill Hall area.

The older parts of the town north of its centre are built upon a relatively flat-lying alluvial fan extending west from the area of St Mary's Priory to Cantref and of similar age to the moraine.

[7] In the UK 2011 census, the six relevant wards (Lansdown, Grofield, Castle, Croesonen, Cantref and Priory) collectively listed Abergavenny's population as 12,515.

[15] Remains of the walls of this fort were discovered west of the castle when excavating the foundations for a new post office and telephone exchange building in the late 1960s.

The first Baron was Hamelin de Balun, from Ballon, a small town with a castle in Maine-Anjou near Le Mans.

[18] Owing to its geographical location, the town was frequently embroiled in the border warfare and power play of the 12th and 13th centuries in the Welsh Marches.

In 1175, Abergavenny Castle was the site of a massacre of Seisyll ap Dyfnwal and his associates by William de Braose, 4th Lord of Bramber.

According to popular legend, his raiders gained access to the walled town with the aid of a local woman who sympathised with the rebellion, letting a small party in via the Market Street gate at midnight.

They were able to open the gate and allow a much larger party who set fire to the town and plundered its churches and homes leaving Abergavenny Castle intact.

[17] During the Civil War, prior to the siege of Raglan Castle in 1645, King Charles I visited Abergavenny and presided in person over the trial of Sir Trefor Williams, 1st Baronet of Llangibby, a Royalist who changed sides, and other Parliamentarians.

Owing to the refusal of the chief officers of the corporation to take the oath of allegiance to William III in 1688, the charter was annulled, and the town subsequently declined in prosperity.

Chapter 28 of the 1535 Act of Henry VIII, which provided that Monmouth, as county town, should return one burgess to Parliament, further stated that other ancient Monmouthshire boroughs were to contribute towards the payment of the member.

[22] Abergavenny was celebrated for the production of Welsh flannel, and also for the manufacture, whilst the fashion prevailed, of goats' hair periwigs.

[23] Adolf Hitler's deputy, Rudolf Hess, was kept under escort at Maindiff Court Hospital during the Second World War, after his flight to Britain.

In the late 14th century the reversion of the feudal marcher barony (with the castle, town and surrounding lands appurtenant) was purchased from John Hastings, 3rd Earl of Pembroke, who had no heirs, by William Beauchamp, the second son of the Earl of Warwick; and he was elevated to the House of Lords as Baron Bergavenny.

[26] From him it has descended continuously, the title being increased to an earldom in 1784; and in 1876 William Nevill [sic] 5th Earl, an indefatigable and powerful supporter of the Conservative Party, was created 1st Marquess of Abergavenny.

[27] Sir Charles reconstructed the house in 1746 with the addition of a nine-bay two-storey Georgian façade with a Doric portico.

The new club, Abergavenny Town F.C., plays at the Pen-y-pound Stadium, maintained and run by Thursday’s football trust, as members of the Ardal South East league (tier 3) for the 2021–22 season.

[45] In 2011 doubts about the future of Abergavenny Cattle Market were raised after Monmouthshire County Council granted planning permission for its demolition and replacement with a supermarket, car park, and library.

The TV series Upstairs, Downstairs, features a character in the second season, Thomas Watkins, the devious Bellamy family chauffeur, who comes from Abergavenny.

Abergavenny Castle is located strategically just south of the town centre overlooking the River Usk.

It was built in about 1067 by the Norman baron Hamelin de Ballon to guard against incursions by the Welsh from the hills to the north and west.

Other listed buildings in the town include the parish Priory Church of St Mary, a medieval and Victorian building that was originally the church of the Benedictine priory founded in Abergavenny before 1100; the sixteenth century Tithe Barn near St Mary's; the Victorian Church of the Holy Trinity; the Grade II* listed St John's Masonic Lodge; Abergavenny Museum; the Public Library; the Town Hall; and the remains of Abergavenny town walls behind Neville Street.

[69] Some psychiatric services are now administered from Maindiff Court Hospital on the outskirts of the town, close to the foot of the Skirrid mountain.

[72] A fourth registered garden, at The Hill to the north of the town, forms part of the grounds of a residential development.

In 1908 following the formation of the Territorial Force the Abergavenny Cadet Corps was formed and affiliated with the 3rd Battalion, The Monmouthshire Regiment.