They are in your cstrike folder.
If you have Steam they are in the cstrike folder INSIDE your
Counter-Strike.gcf gcache file.
For some maps the textures are inside the .BSP, which is in your cstrike/maps folder.
If you have Steam that would be in the cstrike/maps folder INSIDE your
Counter-Strike.gcf gcache file.
Once you have the .BSP, you need to use a program called
Textract to extract the .WAD from it. <<Link coming soon>>
To open Steam Gcache files use GCFScape:
http://www.superjer.com/files/gcfscape129.exe