The castle was only one day's march from Chester, supplies could be brought along the River Dee and there was a ford nearby across to England that could be used at low tide.

[1] The castle and its earthworks were built by 18,000 labourers and masons using local Millstone Grit ashlar and sandstone.

Savoyard master mason James of Saint George was assigned "ad ordiandum opera castorum ibidem" (to undertake the works of the same castle works (referring to all Welsh castle building projects) in April 1278.

Its ground dimensions are a third bigger but it shares the classic shape and style, along with the use of a corner tower as keep (donjon).

Most historians attribute this to input from Edward's premier architect and castle builder James of Saint George[8] Although construction began in 1277 and James of Saint George didn't begin work at Flint until 1280, he was in England from 1278 and was described as "ad ordinandum opera castorum ibidem", that is, charged with the design of the works at Flint.

In 1294 Flint was attacked again during the revolt of Madog ap Llywelyn; this time the constable of the castle was forced to set fire to the fortress to prevent its capture by the Welsh.

With the conclusion to the Welsh Wars, English settlers and merchants were given property titles in the new town that was laid out in front of the castle.

[12] In 1399 Richard II of England was held by Henry Bolingbroke at Flint before being returned to London.

To prevent its reuse in the conflict, the castle was then slighted in accordance with Cromwell's destruction order.

Flint Castle is maintained by Cadw, a Welsh-government body that protects, conserves and promotes the building heritage of Wales.

A spiral staircase was installed in the north east tower in 2017, from where a platform gives views over the Dee Estuary.

[13] A giant iron ring sculpture was due to be placed in the castle grounds but was seen as divisive and the project was shelved — the architects said the sculpture represented the "unstable nature of the crown", but criticis interpreted the symbol as representing the subjugation of the Welsh people.