In both The Castle of Otranto (TCO) and Vathek there are mentions of vast amounts of space, in TCO the word 'cavern' is often used to describe the space, whereas 'spacious and lofty' was used in Vathek. In TCO the fact that there is a lot of space could be used to highlight the difficulty of her escape; there is so much space but that actually hinders her escape because it means there are only more places to look to get out and a higher potential of getting lost and therefore more trapped.
There are limited amounts of light mentioned in both extracts, 'an imperfect ray of clouded moonshine', 'illuminated by torches and braziers', 'labyrinth of darkness' - all of these words back up that darkness is seen as a scary thing, by that you don't know what is in the shadows, and so it adds to the sense of uncertainty and fear.
The vault that leads to the church in TCO is described as 'dark and dismal', so even the way to safety is not actually comforting to the character. The fact that the description of the way to the church is so negative fits with the idea that the Gothic genre goes against religion; the place of worship that is supposed to be a safe place is only safer than the castle the character is currently in because it doesn't have Manfred in it.
