The charm of the Cotswold lies in its stone, the yellowish sandy chalk from which the inhabitants built their homes and villages. This is only one of its outstanding features. Others are its fertile woods and grazing lands, the fine views west over the Severn Valley where the chalk hills suddenly break down. There are many neolithic and iron age forts and settlements. Exploring the Cotswolds is best done on the Cotswold Way, a National Trail. The whole of the Cotswold is Area of Outstanding Natural Beauty.