Although Samuel Coleridge never describes in detail the castle in his poem ‘Christabel,’ careful readers can, nevertheless, gather quite a few details of what the castle looked like. Initially, we are only told that the castle has a clock (line 1) and that there are woods about a ‘furlong beyond the castle gate’ (line 26). But further reading reveals other details. After Christabel has ‘rescued’ Geraldine, she invites her to return to the castle with her, assuring her that everyone is asleep, that ‘hall [is] as silent as the cell’ (line 117). This tells us there are likely dungeons below the castle. When the two women arrive at the castle, ‘they crossed the moat,’ (line 123), and Christabel uses a key to open a small door fitted right inside the middle of the large gate (lines 124-126). So now we know there is a moat around the castle, there is a man-door that has a lock on it, and we know there is a large gate. Further, we are told the gate is clad in iron on both sides, and this is where the army that defends the castle marches in and out (lines 127-128). So now we also know the castle holds its own army (which means we can probably assume it also has an armory and barracks for the soldiers). Right inside the gate is a large courtyard leading to the halls, and that the dog kennels are here, as well (lines 136, 144, 145). The courtyards lead to the halls that, in turn, lead to the interior rooms of the castle, and these halls are lit by brands, which ‘are flat, the brands are dying’ (line 156). ‘Brands’ here is most likely a truncated form of ‘firebrands,’ torches made of pieces of wood, usually dipped in tar and placed in iron holders in the walls to light the halls, especially at night. The fact that these are dying also tells us the women have probably returned to the castle in the wee hours of morning because the brands were meant to burn through the dark hours of the night. There are also tall shields, probably coats of arms, hanging in niches, carved out hollows, in the walls (lines 162-163).
The women finally reach Christabel’s chambers after they have had to ‘steal their way from stair to stair’ (line 168), so we know the castle has several levels, and as they enter Christabel’s room, ‘Geraldine press[es] down / [t]he rushes of the chamber floor’ (lines 173-174). Rushes are any number of species of tall grasses that were commonly cut and strewn on the floor of medieval homes for the purpose of sanitation and insulation. Because Christabel’s father is a baron, a member of the aristocracy and rich, it is more likely, at least according to Woodbury (3 May, 2016), that these ‘rushes’ are mats woven of rushes. So Christabel’s room probably had woven mats on the floor. In addition, in her chamber, the walls and furniture are heavily ‘carved so curiously / Carved with figures strange and sweet’ (lines 178-179). We also know that one of the carvings on the wall is an angel that holds on its feet a lamp with two silver chains (lines 182-183).
In the next part of the poem, we learn a bit more. There is a heavy bell that is rung each morning by the sacristan (lines 332, 339-340), the keeper of the local parish church and sacristy. Most castles either enclosed or had on its grounds its own chapel. That is likely the case here. Christabel and Geraldine hear the morning bells and awaken, dress and ‘pacing both into the hall / And pacing on through page and groom / Enter the Baron's presence-room’ (lines 394-396). We already know the castle has multiple halls and hallways, but we glean a bit more information here. The women go ‘pacing on through page and groom.’ Pages were young male servants and grooms were stable boys/men in charge of taking care of the horses. Since we can assume the women did not literally go through them, we should instead assume they went through the servants’ quarters and the stable area to arrive at the Baron’s presence-room, a room, usually grandly and lavishly decorated—the purpose of this room was to impress—where the rich would receive guests, and since the women had to go through other areas of the castle, one that was likely on the opposite side from the living quarters.
In summary, what we end up with is a fairly complete picture of a typical medieval castle: the castle is surrounded by a moat and protected by a large iron-clad gate. It likely houses an army and any accoutrements and housing the soldiers would need, as well as a dungeon below. There is a large courtyard; halls lit by brands and decorated with shields, probably bearing the family’s coat of arms; carpeted (at least with mats) chamber rooms with intricately carved walls and furniture; servants’ quarters; stables; a presence-room; and a chapel, either within the wall or close by on the castle grounds.