Some dismiss the use of these techniques in archaeology, arguing the methods aren't that new, and demonstrate only evolutionary, rather than revolutionary, improvement. But Stonehenge is a World Heritage Site spread over a large area and while it has been intensively studied for decades, physical digs are now extremely restricted. Instead, over the past four years, the Stonehenge Hidden Landscape Project (SHLP) – a collaboration between the universities of Birmingham, Vienna, Bradford, St Andrews, Nottingham and Ghent with the National Trust and English Heritage – used geophysical survey techniques such as earth resistance, magnetometry, ground-penetrating radar and electromagnetic induction.