This map photograph was taken for the RSA archives.

From their blog site:

Richard Horwood’s map of London: the cartographer Richard Horwood had sought the support of the Society in 1791 for a new map of London, which aimed to show and number each individual building in the cities of London and Westminster, the borough of Southwark and some adjacent areas. Although the Society did not feel it could give an award until the map was finished, Horwood was able to go on and produce his map, which was completed and printed in 1799.