The open grasslands that characterize
the chalk downlands of the Salisbury Plain today
developed gradually as a result of increases in
animal herding and crop cultivation from the
fifth millennium BC onwards. Long barrows,
communal burial mounds of the Early Neolithic
period (fourth millennium BC), occupied this
landscape for many centuries before the first
known constructions began at Stonehenge
itself. Also belonging to this era is the so-called
cursus, an enigmatic 3 km long and 100 m wide
strip delineated by two earthen banks, running
roughly east to west. It is only barely visible today