I realized that I didn't actually know that much about the different parts of a castle, despite playing D&D for forever and seeing them everywhere. I jumped on the internet and began absorbing as much as I could.
I think I have a good understanding of the components and terminology of a castle now, but I have one nagging question. In the wikipedia.org article on Citadel, there is this line at the bottom of the second paragraph: " A citadel is also a term of the third part of a medieval castle, with higher walls than the rest. It was to be the last line of defense before the keep."
What the heck does this mean? I have looked for pictures illustrating this sort of castle that contains both a citadel and keep, and have found nothing. I have also tried googling various combinations of "citadel", "keep", "great hall", "great tower", "donjon", "castle", etc. and have also come up empty handed. I also tried to find some sort of standardized list of compnonents of castles where "citadel" is the third component. Nothing.
Can anybody shed some light on this for me please? I am very confused.
The problem you're running into is that medieval castles were not in any way standardized, and so no such list can exist without being heavily generalized. The wikipedia article is also wrong. To the extent historians use the word citadel, it is almost always to refer to the heavily fortified core of a walled city, where the garrison may retreat when the walls are compromised. These are also called urban castles. I don't have any idea what the "third part" is supposed to be.
Allow me to provide an example. Beginning in the late 11th century, stone great towers came into vogue in European castle building. These are often called donjons or keeps, and were placed in the center of the castle and surrounded by a curtain wall. The great tower would be the last refuge of the defenders should the curtain wall fall.
But around the year 1200 (there are some earlier examples as well), the fashion changed. The traditional great tower gradually disappeared. Instead, castles were built concentrically. Typically, this consisted of two walls, a lower outer wall, and a higher inner wall, both studded with towers. In this period, the great tower was simply the largest of the towers set in the inner wall, not a huge square free standing structure as in the 12th. There was also frequently an elaborately fortified gatehouse which projected from the outer wall, called a barbican.