Cardiff Castle is a medieval castle with an original motte and bailey construction built in the late 11th century by Norman invaders on top of a 3rd-century Roman fort. The first fort was probably built about AD 55 and occupied until AD 80. Later replaced with a sequence of two much smaller fortifications, in the middle of the 3rd century a larger fort was built in order to combat the pirate threat along the coast.
Cardiff castle was commissioned either by William the Conqueror as early as 1081 on his return from his pilgrimage to St Davids, or by Robert Fitzhamon around 1091, and rebuilt in stone (probably by Robert of Gloucester) in the 12th century. During this time, a shell keep was added and substantial defensive walls erected.
The Castle was repeatedly involved in the conflicts between the Anglo-Normans and the Welsh. It was attacked several times in the 12th century, and stormed in 1404 during the revolt of Owain Glyndŵr.