And did those feet in ancient time
Walk upon England's mountains green?
And was the holy Lamb of God
On England's pleasant pastures seen?
And did the Countenance Divine
Shine forth upon our clouded hills?
And was Jerusalem builded here
This is an idealised view of England. It is a line repeated at the end of the poem with a variation, a device known as  anaphora .
And Did Those Feet In Ancient Time