It is famous for having many stone structures carved into the rock. The long-hidden site was revealed to the Western world by the Swiss explorer Johann Ludwig Burckhardt in 1812. It famous description "a rose-red city half as old as time" is the final line of a sonnet by the minor Victorian poet John William Burgon, which won the Newdigate Prize for poetry, given at Oxford, 1845. Burgon had not actually visited Petra, which remained inaccessible to all but the most intrepid Europeans, guided by local guides with armed escorts, until after World War I.