Grosmont Castle

The ruins of Grosmont Castle stand on a hill in Grosmont, Monmouthshire, Wales. After invading England in the year 1066, the Normans created the first castle on this site. THe site is free to visit but is under control of CadW. The castle was the site of frequent Wesh uprisings and formed a lordship named 'Three Castles' along with White and Skenfrith Castles.

Visiting Grosmont Castle


Although the castle itself is easy to find in the small village of Monmouth, the parking is not clearly signposted. There is no dedicated car park for the castle; however, one may find a small parking area on the left of the road past the Angel Inn, which is well signposted.


You may visit the Grosmont ruins for free, as it is an open-access site under the guardianship of Cadw.


Open year-round; visit at any reasonable time during daylight hours

Daily 10:00 am - 4:00 pm.

Location & Access





United Kingdom

Visitors may access Grosmont Castle either via the B4347, about 10 miles (16.09 km) from Monmouth, or from Abergavenny via the A465.

Know Before You Go

  • Dogs are welcome at the castle site
  • There are picnic tables near the castle to enjoy a packed lunch for the family
  • The castle is a no-smoking area
  • There are steps up onto part of the wall for impressive views of the surrounding countryside
  • There are no public toilets on the castle site, but one may access these facilities in the village. 

History of Grosmont Castle

Grosmont Castle played a pivotal role in defending the region from Welsh attacks, and the Normans made use of their position to control key areas of the troublesome border country. The early earth and timber castle was later changed to stone and extensively remodelled over the centuries. 

Time Line


Historians suggest that William Fitz Osbern, the Earl of Hereford, commissioned the first timber and earthwork castle on the Grosmont Castle site. The Earl constructed the castle in the wake of the Norman invasion of England to protect the passage between Wales to Hereford. 

-Early 12th Century

The Nobel Pain Fitz John assumed ownership of the castle as part of his royal offices to King Henry I. 

-1135 (Revolt)

In the wake of a significant Wesh revolt, King Stephen created the lordship of "Three Castles," combining Grosmont, White, and Skenfrith Castles in a powerful, defensive ring. The Three Castles played a pivotal role in protecting the Normans from the predominantly Wesh territories for hundreds of years. 


After the Welsh attack at Abergavenny Castle, the Crown prepared Grosmont for a similar attack, and the Crown spent £15 on fortifying the structure under the care of Ralph of Grosmont.

-1201 (Upgrades)

King John granted Grosmont and the sister castles to Hubert de Burgh, a close aide to the King. Hubert began extensive upgrades on Grosmont Castle and replaced the wooden hall block in stone. 


During the war with the French, Hubert was imprisoned, and King John gave his lands and the Three Castles to William de Braose.

-1207 (Captured)

De Braose fell out of royal favour, and King John stripped him of the castle and lands. However, his son, William de Braose, took advantage of the First Barons War and recaptured Grosmont Castle. 

-1219 (Rebuild)

Hubert reclaimed his royal favour under Henry III, became Earl of Kent, and recovered ownership of the Three Castles. He conducted extensive rebuilding of Grosmont Castle and added a gatehouse and three mural towers. He also rebuilt the timber defence walls in stone.


Hubert once again fell from royal favour and was deprived of his castles and lands in the fickle game of political fortunes. A royal servant named Teutonicus took over command of Grosmont. 

-1233 (Night Attack)

King Henry camped within the grounds of Grosmont Castle with his allies in a show of force against the Welsh rebellion of Richard Marshall and his followers. Richard forced the encampment to retreat in a daring night attack. 


Hubert fell back into favour and recovered Grosmont, only to lose the favour yet again in 1239. Once again, Walerund took command of Grosmont, who completed the addition of a chapel in the castle. 

-1254 (Increased Fortification)

King Henry granted Grosmont with its sister castles to his eldest son, the future King Edward. And in an increased threat of Welsh attack, the royal forces garrisoned Grosmont to its capacity. The danger, however, did not come to fruition. 


The Crown appointed Edmund, Earl of Lancaster, as the owner of the Three Castles. The castles remain property of Lancaster's earldom and afterwards duchy. After King Edward's conquest of the Welsh in 1282, the military function of the Grosmont Castle diminished. 

-Mid-14th Century (Residential Upgrades)

Henry of Lancaster extensively remodelled the inside of the castle. His successor, Henry of Grosmont, was said to have helped, too. The increasingly domestic role of the castle resulted in a suite of comfortable apartments with the castle. They also created a deer park on the castle grounds, enhancing the new residential role of the site. 

-15th Century (Siege)

Grosmont Castle once again took a military role during the uprising of the Welsh Owain Glyndŵr in the early 1400s. After the English victory of Richard Beauchamp close to Grosmont in 1404, Gruffudd, the son of Glyndŵr, laid siege to Grosmont Castle. Prince Henry sent forces to relieve the siege, and the castle remained standing. 


Grosmont castle fell into disuse. By 1563, a historical survey noted that the bridge had fallen and the interior had fallen into ruin. This state was likely due to the elements and looting of the valuable stone. 


Historical records refer to the site as ruinous. 


The 6th Duke of Beaufort, Henry Somerset, purchased the "Three Castles." 


The 9th Duke of Somerset, Henry Somerset, sold the castle to a soldier and historian named Sir Joseph Bradney.


Frances Lucas-Scudamore placed the castle into state care, and the state conducted clearing and conservation of the site. 


Grosmont Castle is listed as a timber castle and also a masonry castle. It is a scheduled monument protected by law and a Grade I Listed building.  

Grosmont Castle Occupants

  • 1106: William Fitz Osbern, the Earl of Hereford, built the first timber and earthwork castle.
  • Late 11th Century: Robert de Breteuil inherited the castle but was disposed of his lands by Willam the Conqueror. 
  • Early 12th Century: Pain Fitz John took ownership of Grosmont Castle.
  • 1201: Hubert de Burgh began construction on Grosmont Castle. 
  • 1207: William de Broase took possession of the Grosmont Castle, and later his son recaptured the castle from the Crown. 
  • 1233: King Henry III and his allies camped in the Grosmont Castle grounds, and Richard Marshall and his Wesh forces forced the English to flee. 
  • 1234: Walerund Teutonicus took possession of the castle.
  • 1267: Edmund the Earl of Lancaster took control of the castle, and later his son Henry of Grosmont. 

 Images of Grosmont Castle

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Grosmont Castle Grosmont Castle

Images Supplied and licensed from Shutterstock Standard Licence Package

Grosmont Castle Q&A

Was Grosmont Castle the Scene of Any Bloody Battles?

In 1405, Glyndŵr dispatched an 8,000-strong force to attack Grosmont Castle under Rhys Gethin's command. When the King sent a relief force, Prince Henry wrote to his father, informing him of the 'great slaughter inflicted' on the welsh. 

Although there is no confirmed verification, they likely suffered a significant loss of lives, including Rhys Gethin, their commander. Some historians suggest that between 800 to 1,000 Welshmen may have lost their lives at Grosmont Castle.

How Old Is Grosmont Castle?

The first defensive structure was a basic wood and earthwork fort typical of the early 12th century fortifications. In the early 13th century, stone replaced the wooden structure, and towers, a gatehouse, and curtain walls were added. The 14th-century modifications included an additional north range in the north tower and a southwest tower expansion to the height of five stories.

What Remains of Grosmont Castle?

After a relatively active part in the area's history, the castle was abandoned in the 16th century.

Most of the defensive walls remain standing, along with two western towers, the outer walls of a main building on the eastern side, a 13th-century gatehouse entrance, and a four-sided tower. Only a chimney and remnants of the inner sidewall still stand with a visible surrounding ditch in the north. 

Location of Grosmont Castle

Grosmont Castle is located on a flat, elevated plateau a short distance northwest of Grosmont village in Monmouthshire, Wales. Historians suggest that the castle was raised on an earlier motte, although some suggest that the castle was a new masonry built in the 12th or 13th century. 

However, historians agree that the castle did occupy some sort of manorial centre that was active before they built Grosmont Castle. Evidence suggests that the Normans built the first castle on the site around 1154 using timber and earthwork surrounded by a ditch that was typical of the architecture of the period.