Pokemon white help? bianca told me to go to relic castle but i can't find it?

Go to Nimbasa and leave south. When you reach the motorway turn left and then go up when you can. Follow the path and you will end up in a desert. Wander around until you fina stairs leading down with 5 or 6 statues surrounding it. Go down there. If you find a turret, go right from there.