Following the conquest of 1066, the Norman invaders were determined to consolidate their hold on both the defeated Anglo-Saxons and the recalcitrant Welsh. Wales has always presented a problem to those determined to impose their will on the Brititish Isles. The Normans were inclined to take no chances, so they set to work on a series of immense fortresses, the imposing remains of which can be seen today in places such as Chepstow and Pembroke. Two hundred years later, their descendants were still having trouble, so, in 1277, King Edward I embarked on the so-called “Conquest of Wales.” With the defeat in 1282 of Llywelyn ap Gruffydd, the last independent prince, his annexation was complete. Like his forefathers, Edward then set to work in a mania of castle-building. The most impressive of his great fortresses, Caernarfon, Harlech, Beaumaris and Conwy, survive largely intact to this day. If you have time to visit only one, Caernarfon should be your choice. It is not the largest castle in Wales, however. That distinction belongs to Caerphilly.