The protected city

Methodology

Every listed building, conservation area, scheduled monument, registered park and world heritage site inside the 33 London authorities, from planning.data.gov.uk. Listed buildings come from Historic England's national list and are coloured by grade — Grade I is roughly the top 2.5% nationally, so a linear colour would lose them among the Grade IIs. Each entity is drawn at its published centroid, which for a conservation area is the middle of an area rather than a building.