Caernarfon Castle is a medieval fortress in Caernarfon, Gwynedd, north-west Wales cared for by Cadw, the Welsh Government's historic environment service. There was a motte-and-bailey castle in the town of Caernarfon from the late 11th century until 1283 when King Edward I of England began replacing it with the current stone structure. The Edwardian town and castle acted as the administrative centre of north Wales and as a result the defences were built on a grand scale. There was a deliberate link with Caernarfon's Roman past nearby is the Roman fort of Segontium and the castle's walls are reminiscent of the Walls of Constantinople. While the castle was under construction, town walls were built around Caernarfon. The work cost between £20,000 and £25,000 from the start until the end of work in 1330. Despite Caernarfon Castle's external appearance of being mostly complete, the interior buildings no longer survive and many of the building plans were never finished. The town and castle were sacked in 1294 when Madog ap Llywelyn led a rebellion against the English. Caernarfon was recaptured the following year. During the Glyndŵr Rising of 1400–1415, the castle was besieged. When the Tudor dynasty ascended to the English throne in 1485, tensions between the Welsh and English began to diminish and castles were considered less important. As a result, Caernarfon Castle was allowed to fall into a state of disrepair. Despite its dilapidated condition, during the English Civil War Caernarfon Castle was held by Royalists, and was besieged three times by Parliamentarian forces. This was the last time the castle was used in war. Caernarfon Castle was neglected until the 19th century when the state funded repairs. In 1911, Caernarfon Castle was used for the investiture of the Prince of Wales, and again in 1969. It is part of the World Heritage Site "Castles and Town Walls of King Edward in Gwynedd". The first fortifications at Caernarfon were built by the Romans. Their fort, which they named Segontium, is on the outskirts of the modern town. The fort sat near the bank of the River Seiont; it is likely that the fort was positioned here due to the sheltered nature and as traffic up the Seiont would have been able to supply Segontium. Caernarfon derives its name from the Roman fortifications. In Welsh, the place was called "y gaer yn Arfon", meaning "the stronghold in the land over against Môn"; Môn is the Welsh name for Anglesey. Little is known about the fate of Segontium and its associated civilian settlement after the Romans departed from Britain in the early 5th century. Caernarfon Castle's design was partly influenced by a desire to make the structure impressive as a symbol of the new English rule in Wales. This was particularly acute as Caernarfon was made the centre of government in the northern part of the country. The Edwardian castle's layout was mostly dictated by the lay of the land, although the inclusion of the previous castle's motte played a part. It is a narrow enclosure, roughly in the shape of a figure eight. It was divided into two enclosures, upper and lower "wards" in the east and west respectively, with the eastern containing royal accommodation, although this was never completed. The divide was supposed to be established by a range of fortified buildings, however these too were never built. Studded along the curtain wall are several polygonal towers from which flanking fire could be deployed. There were battlements on the tops of walls and towers, and along the southern face were firing galleries; it was intended to included galleries along the northern face but they were never built. In the opinion of military historian Allen Brown, this combined to make Caernarfon Castle "one of the most formidable concentrations of fire-power to be found in the Middle Ages". Most of the northern towers stand had four-storeys including a basements. The Eagle Tower at the western corner of the castle was the grandest. It has three turrets which were once surmounted by statues of eagles. The tower contained grand lodgings, and was probably built for Sir Otton de Grandson, the first justiciar of Wales. A basement level contained a water gate, through which visitors travelling up the River Seiont could enter the castle. Water was drawn from a well in the eponymous Well Tower. Caernarfon's appearance differs from that of other Edwardian castles through the use of banded coloured stone in the walls and in its polygonal, rather than round, towers. There has been extensive academic debate over the interpretation of these features.