Linwood was most famously home to the Hillman Imp and its many derivatives (1963-1976). Other models to have been built there include the Hillman Hunter and its derivatives (1970-1976), Hillman/Talbot Avenger (1976-1981), fastback Sunbeam Rapier/Alpine (1970-1976), and the Talbot Sunbeam hatchback (1977-1981).
The plant is situated on the A761 (Linwood Road). Coming from the direction of Glasgow, you will find the plant before you reach Linwood itself.
I bought a copy of the Bartholomew Glasgow Streetfinder Atlas. The Rootes plant is on Map 45, G14. If you look at Map 29, G13 you will see an area identified as "Phoenix Business Park". This is the Pressed Steel site.
If you have Google Earth, you can see recent satellite images of the Linwood site by opening this .kmz placemark file:
The following photos were taken on 20 April 1998. Much more demolition work has taken place since and only a few buildings are left today.
You should also see David Pentland's Linwood site. It contains photographs comparing the site in 1963 to 1997.
What they did to the Pressed Steel site.