The lands were granted to Henry de Lacy, Earl of Lincoln, who began to build a new walled town, colonised by immigrants from England, protected by a substantial castle and surrounded by deer parks for hunting.

Denbigh Castle is dominated by a triangle of three octagonal towers that forms its main entrance, considered by the historian John Goodall to be "the most architecturally sophisticated gatehouse of the thirteenth century".

[1] The patrimony controlled the pastoral farming lands on the Denbigh Moors and formed a royal residence, llys, for the Welsh princes.

[4] It is uncertain what form it took or exactly where on the current castle site it was located, but it included a bakehouse, buttery, chapel and a hall, and it became Dafydd's main stronghold.

[6] The King created a new lordship to govern the district around Dinbych, which he renamed Denbigh and granted these lands to Henry de Lacy, the Earl of Lincoln.

[3] With the help of James of St George, the King's master mason, Edward and Henry made plans for the construction of a new castle to govern the area, symbolically placed on top of the former llys.

[10] The castle and town formed part of a wider landscape controlled by de Lacey, including a nearby manor, a dovecote, barn and fishponds, which were all important symbols of lordship during the period.

[11] The town walls enclosed an area approximately 9.5 acres (3.8 ha) in size and held 63 burgesses in 1285, each of which promised to provide an armed man to help protect the settlement.

[13] From the earliest days of the new settlement; the inhabitants began to spread out beyond the walls onto the flatter ground further down the hill, spurred on by the limited space and poor water supply in the inner town.

[14] This was unusual compared to the experience of other walled towns established in Wales at the time and within fifty years the external villa mercatoria had come to cover around 57 acres (23 ha).

[21] Jasper Tudor, the Earl of Pembroke and a Lancastrian supporter, was declared the constable of the castle by Henry VI in 1457 but the fortification remained in the hands of the Yorkists.

[23] The war then turned in favour of the Yorkists and despite the castle's new garrison holding out for several months under Roger Puleston, it was recaptured by Sir Richard Herbert in late 1461.

[29] Robert Dudley, later made the Earl of Leicester, was granted a lease of the castle in 1563, partially because the Crown was trying to reduce the costs of maintaining the dilapidated property.

[29] During Dudley's tenure, Denbigh Castle was used as a place of imprisonment for those considered traitors by the officials of the Crown, including many dissidents towards the Elizabethan religious settlement.

The most famous such prisoner was the Welsh poet and underground Catholic schoolmaster Richard Gwyn, who was imprisoned at Denbigh Castle from September 1581 to the Spring of 1582.

[31] On 25 October 1970 Pope Paul VI presided over the canonization ceremony in Rome for St. Richard Gwyn, as one of the Forty Martyrs of England and Wales.

[35] During his rule, Dudley also built a large Anglican parish church in the walled town, possibly intending it to become a cathedral and carried out some minor repairs to the castle but little other work was completed before his death in 1588.

[36] When the First English Civil War broke out in August 1642, North Wales was solidly Royalist, and Denbigh Castle was held by a garrison of 500 under Colonel William Salesbury, who made repairs to the defences.

[38] Mytton returned the next year with additional equipment and placed the castle and the walled town under a close siege in April 1646, erecting earthwork bastions for his guns along the eastern site of Denbigh.

[40] With only one artillery piece of his own and no Royalist reinforcements likely, Salesbury's position appeared hopeless but he held on, arguing that he had given assurances to the King that he would not surrender the castle.

[41] Finally, Charles I sent Salebsury a message, personally ordering him to give up Denbigh; after negotiations, Salesbury agreed to surrender on good terms on 26 October.

[52] In the middle of the 19th century, the historian John Williams observed that the walled town remained otherwise deserted, with only three irregular rows of cottages, holding a total of 163 inhabitants; these dwellings attracted complaint from the writer Samuel Lewis, who argued that they "materially diminished the interest excited by the ruins".

[70] Further south is the Pitcher House Tower, probably used for storing water during the summer months and the Green Chambers, so called because of the colour of their Gwespyr stonework.

[71] The chambers have basements specially designed for the storage of meat and wine and the upper storeys originally contained exceptionally fine accommodation.

[79] Only the foundations of the Exchequer Gate on the western side of the walls remain but the gatehouse would originally have been protected by two circular towers, with a rectangular talus base to prevent undermining.

[81] The gatehouse is built from white limestone and yellow sandstone, with the stonework forming a chequered design; this was a common decorative approach at the time and would have symbolised local civic pride.