Where can I get the soundtrack?

[dahlas]

Does anyone know a good website or a way to get it from the game files?

[VdeVeer]

There's actually no soundtrack, as it consists of ambient loops and short stacks of sounds. But, http://www.thief-thecircle.com/media/main/ has the official credits track and some fan mixes which you might be interested in. The site's part of ttlg.com where the core fanbase hangs out mostly.

[VdeVeer]

http://www.thief-thecircle.com/media/music/ <-- a more direct link

[dahlas]

It says page couldn't be found when I click on a song.

[constancejill]

GOG has a pseudo soundtrack here : https://www.gog.com/downlink/file/thief_gold/10973 though I guess you'll need both to be identified there and to have bought the game from them to download it.
As mcela stated though, there is no actual soundtrack, what GOG provides seems to me more like some kind of fan mix of the various ambient musics from the game's levels and some musics from the videos with occasionally some in-game sounds added in there.
Now if you want the actual music files from the game, take your favourite archiver, open snd.crf as a .zip file, and have fun exploring in there ;) ... seems like they are mostly under /sfx/, along with various other sound effects.

[😎 𝓣𝓪𝓯𝓯𝒆𝓻𝔀𝓸𝓬𝓴𝔂 😎]

Try here for Child Of Karras' fan mixes: http://thiefmissions.com/music/