The plaque on the side of the building reads: 'This Fragment is the remains of the building where Edward I held his Parliament A.D. 1283. in which was passed the Statute of Rhuddlan securing to the Principality of Wales its judicial rights and independence.' The Statute of Rhuddlan was created in 1284 after the conquest of Wales by the English King Edward I. After the defeat of Llywelyn ap Gruffydd (Llywelyn the Last) in 1282, Wales was incorporated into England and Edward set about pacifying the new territory. The Statute was an important and influential document which introduced the following measures: it divided north Wales into the counties of Anglesey, Merioneth, and Caernarfon, introduced the English common law system, and allowed the king to appoint royal officials such as sheriffs, coroners, and bailiffs. Some Welsh customs were allowed to remain, such as the specifics of inheritance, and the Marcher Lords retained most of their independence, as they had prior to the conquest. The Statute remained in effect until Henry VIII's Act of Union in 1536. Source: http://www.wordiq.com/definition/Statute_of_Rhuddlan