An armchair archaeologist has identified nearly 2,000 potentially important sites in Saudi Arabia by using Google Earth and without visiting the country.
David Kennedy, a professor of classics and ancient history at the University of Western Australia, used the satellite maps to pinpoint 1,977 potential archaeological sites, including 1,082 teardrop-shaped stone tombs.
Dr Kennedy told New Scientist magazine that he had verified that the images showed archaeological sites by asking a friend working in Saudi Arabia to photograph the locations.
Aerial and satellite imaging has been used in Britain to locate Iron Age and Roman sites as well as Nazca lines in Peru and Mayan ruins in Belize.
Few archaeologists have been given access to Saudi Arabia because of fears that focusing attention on civilisations which flourished before the rise of Islam could undermine the state religion.
In 1994, a council of Saudi clerics was reported to have issued an edict that preserving historical sites "could lead to polytheism and idolatry" - both punishable by death.
Saudi Arabia's rulers have, in recent years, allowed archaeologists to excavate some sites, including the spectacular but little-known ruins of Maidan Saleh, a 2,000-year-old city, but access to ancient sites has remained severely restricted.