Twycross uses a lot of stone and brick as walls for its enclosures, as even the meerkats have a stone wall around them. Was there a conscious effort to create red "barns" for the apes or are the buildings heritage listed? It seems like the stones work well for this snow leopard exhibit, and perhaps the holding area blends into the background. One thing that I will say about this zoo is that it seems it is a "must-see" facility simply for its fabulous animal collection!
This is the left hand end of a long enclosure which was under construction at the time. For the view from the other end showing the long window of the coffee bar and restaurant see Gigit's recent photo [url=http://www.zoochat.com/41/snow-leopard-17-october-2012-294780][/URL]
This is the newest large enclosure at the zoo and the stoniest.
AFAIK, none of the zoo buildings are listed (or likely to be)