The first castles were actually started in the 10th century in France, but they didnt really become normal until the 11th century, and alot of the proliferation of castles came down to the weakening of central rule in France and the rise of decentralised power (not too dissimilar to the story of the proliferation of the tower house in later medieval Ireland). The illustration shows a castle in what is termed the high middle ages, its based on Irish castles from around the late 12th century, with the first wave of Anglo-Norman invaders, as well as castles from the height of Anglo-Norman power in Ireland, the 13th century. There is some debate as to whether the Gaelic Irish had built castles before the arrival of the Normans, there are some likely candidates but without excavation we won't know for sure. Whether or not the Irish built castles themselves, the Anglo Normans were certainly the first ones to build castles on a large scale, most were medium sized in comparison to the rest of Europe but the likes of Trim are impressive, even in a European scale.
The castle in the illustration is from a wide selection of early Anglo-Norman castles. The central keep (the large white building), or donjon if you prefer, is based on a combination of Greencastle, Maynooth, Trim and a small bit of Carrickfergus. Notice the second white building outside the main keep, that is the hall, where entertainments, meetings and feasts were held, essentially the public venue. The Hall here is based on one in Adare castle as is in the inner gate tower beside it. The outer gatehouse is based on Limerick castles gatehouse which is defended by a drawbridge, while the inner gatehouse is defended by a portcullis. The larger circuit wall is based on Trim castles' wall on the outer bailey while in the inner bailey is based on Carrickfergus. The overall plan is a mix of Carrickfergus and Trim, though its not exactly like either really.
In the inner bailey the castle has gardens, both for recreation and growing food. Notice as well how white the keep is, like the later tower house image I did, the earlier castles generally had Harling on their outside, making them gleam white in the landscape. I wasnt sure whether this was just for the keep or the whole castle, so I went for the most important buildings only here, the Keep and Hall. Outside of the castle there is a deer park, which alot of castles had, Deer parks contained deer which were the for the lord and his retinue to hunt. Also deer parks often had forestry which the lord used for wood and even sometimes fish ponds, like the one in the top edge of the image. These were sometimes protected by a palisade and embankment to keep poachers out. Poaching was not unusual though but the fines gathered from caught poachers was a source of income for the lord, so unlike in movies, poachers were rarely killed. Another feature normally seen outside of castles (as well as walled towns) were Inns just outside the gates, as seen here, as after a certain time of night the gates would be closed till morning, so those who arrived late, could stay in the inn till the gates opened again.
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