es
there were added a series of polygonal bastions, of the type found at
Caerwent. To this period also belongs the massive rampart, over 10 ft.
thick, and the north gateway, one of the most perfect Roman gateways in
Great Britain. After the departure of the Romans the walls became
ruinous or were partly pulled down, perhaps by sea rovers from the
north. In this period of anarchy the native princes of Glamorgan had
their principal demesne, not at the camp but a mile to the north at
Llystalybont, now merely a thatched farmhouse, while some Saxon invaders
threw up within the camp a large moated mound on which the Normans about
the beginning of the 12th century built the great shell-keep which is
practically all that remains of their original castle. Its builder was
probably Robert, earl of Gloucester, who also built Bristol castle. Then
or possibly even earlier the old rampart was for two-thirds of its
circuit buried under enormous earthworks, the remainder being rebuilt.
It was in the keep, and not, as tradition says, in the much later "Black
Tower" (also called "Duke Robert's Tower"), that Robert, duke of
Normandy, was imprisoned by order of his brother Henry I. from 1108
until his death in 1134. Considerable additions of later date, in the
Decorated and Perpendicular styles, are due to the Despensers and to
Beauchamp, earl of Warwick, while the present residential part is of
various dates ranging from the 15th century down to the last half of the
19th, when a thorough restoration, including the addition of a superbly
ornamented clock-tower, was carried out. The original ditch, about 20
yds. wide, still exists on three sides, but it is now converted into a
"feeder" for the docks and canal. Geoffrey of Monmouth was at one time
chaplain of the castle, where he probably wrote some of his works. The
scene of the "sparrow-hawk" tournament, described in _Geraint and Enid_,
one of the Arthurian romances, is laid at Cardiff.

On the conquest of the district by the Normans under Fitz Hamon, Cardiff
became the caput of the seigniory of Glamorgan, and the castle the
residence of its lords. The castle and lordship descended by heirship,
male and female, through the families of De Clare, Despenser, Beauchamp
and Neville to Richard III., on whose fall they escheated to the Crown,
and were granted later, first to Jasper Tudor, and finally by Edward VI.
in 1550 to Sir William Herbert, afterwards created Baron Herbert of
Cardiff and earl