Hubert rebuilt the castle in stone, beginning with a new hall and then, on regaining the property in 1219, adding a curtain wall, gatehouse and mural towers.

[3] Grosmont was one of three fortifications built in the Monnow valley around this time to protect the route from Wales to Hereford, possibly by the earl himself.

[6] The earl's landholdings in the region were slowly broken up after William fitz Osbern's son, Roger de Breteuil, rebelled against the Crown in 1075.

[13] Once released from captivity, Hubert regained his grip on power, becoming the royal justiciar and being made the Earl of Kent, before finally recovering the Three Castles in 1219 during the reign of Henry III.

[16] King Henry led an army into Wales in 1233 against the rebellious Richard Marshal, the Earl of Pembroke, and his Welsh allies, and camped outside Grosmont Castle that November.

[17] Richard carried out a night attack on their encampment and, while not taking the castle itself, forced the rest of the King's army to flee in confusion.

[18] The Welsh threat persisted, and in 1262 the castle was readied in response to Prince Llywelyn ap Gruffudd's attack on Abergavenny in 1262; commanded by its constable Gilbert Talbot, Grosmont was ordered to be garrisoned "by every man, and at whatever cost".

[20] By 1538, Grosmont Castle had fallen into disuse and then into ruin; a 1563 survey notes that its bridge had collapsed and that, although the outer walls were intact, the interior was in decay and its building materials inside had either been removed or were rotten.

[23] The castle was placed into the care of the state in 1922 by Frances Lucas-Scudamore, and conservation work was carried out, including clearing the basement of the north block of debris.

[24] In the 21st century, Grosmont Castle is managed by the Welsh heritage organisation Cadw and is protected under UK law as a grade I listed building.

[25] Grosmont Castle overlooks the village of the same name, and in its current form dates mostly from the work carried out by Hubert de Burgh with later 14th-century additions.

[6] The inner ward forms a stone castle with a gatehouse, two circular mural towers, a hall and a north accommodation block, the whole being protected by a ditch.

[6] Originally other timber buildings would have been raised against the outer stone wall as accommodation for the castle's servants, but only limited traces of these survive.

[26] The gatehouse was originally a two-storey, rectangular tower with 14th-century additions, including a buttressed drawbridge pit, but only limited parts of it now survive.