"If you look at the digital terrain models that are produced by Lidar, you can see the individual rooms of buildings where the vaults have collapsed," says Luke Auld-Thomas, an archaeologist at Tulane University and Northern Arizona University, USA, who led the team that made the latest discovery. "You can see columns along the facade of buildings that were used for public facing, administrative activities. So they're actually in very good shape. You couldn't quite move into them, but a lot of them still have standing walls and architectural detail that's quite well preserved."