sentences:  Significant communities in the Great Valley include, from east to west, King of Prussia, Valley Forge, Chesterbrook, Paoli, Malvern, Exton, Downingtown, Thorndale, Coatesville, Parkesburg, and Atglen.The Great Valley forms a natural route to the west from the Philadelphia area.Both the Pennsylvania Turnpike and U.S. Route 202 follow the eastern portion of the valley.