The dungeon believed to have housed Robin Hood when he was caught by the Sheriff of Nottingham is to be surveyed using a laser.
It is part of a major project to explore every cave in Nottingham.
Robin Hood is believed to have been held captive in an oubliette (underground dungeon) located at what is now the Galleries of Justice.
The Nottingham Caves Survey is being conducted by archaeologists based at the University of Nottingham.
The two year project, costing £250,000, has been funded by the Greater Nottingham Partnership, East Midlands Development Agency, English Heritage, the University of Nottingham and Nottingham City Council.
Experts from Trent and Peak Archaeology will use a 3D laser scanner to produce a three dimensional record of more than 450 sandstone caves around Nottingham from which a virtual representation can be made.
David Knight, Head of Research at the Trent and Peak unit, said there will be no actual excavations just the use of the laser.
“The aim is to increase the tourist potential of these sites. The scanning will also make them visible ‘virtually’ which is good in terms of public access because a lot of them are health hazards.
“That’s one of the problems with these caves – they’re very impressive but access is fairly difficult. You can imagine the health and safety issues are quite significant.”
The last major survey of Nottingham’s caves was in the 1980s. The British Geological Survey (BGS) documented all known caves under the city.
The Nottingham Caves Survey will update the information that made up the BGS’s Register of Caves.
David Knight said: “Once we’ve done the whole lot we’ll be in a position to rank them in order of significance and make a decision on which caves may or may not be opened.”
The area which now makes up Nottingham city centre was once known as Tiggua Cobaucc, which means ‘place of caves’.
The caves date back to the medieval period and possibly earlier. Over the years they have been used as dungeons, beer cellars, cess-pits, tanneries and air-raid shelters.
Today the most famous include the City of Caves in the Broadmarsh Centre, Mortimer’s Hole beneath the Castle, the oubliette at the Galleries of Justice, the cave-restaurant at the Hand and Heart pub on Derby Road and the cellar-caves at the Trip to Jerusalem pub.