For nearly a decade, David Kennedy marveled from behind his computer screen at thousands of mysterious stone structures scattered across Saudi Arabia’s desert. With Google Earth’s satellite imagery at his fingertips, the archaeologist peeked at burial sites and other so-called Works of the Old Men, created by nomadic tribes thousands of years ago.

But he was unable to secure permission to visit the country to observe up close the ancient designs that he and amateur archaeologists had studied from their desktops.

Last month, after announcing he had identified nearly 400 stone “gates,” Dr. Kennedy received the invitation of a lifetime from Saudi officials to investigate the hidden structures from a helicopter.

“They are absolutely astonishing,” said Dr. Kennedy, who recently retired from the University of Western Australia. “From 500 feet, you can see the vital details of structures that are invisible in the fuzzy image on Google Earth.”