Question juridique clé
Whether the authorities had to determine the 'developed ground' for a new building by reference to the terrain before the first historic construction.
Solution extraite
For a new building, the authorities could rely on the terrain existing when the building application was filed; they did not have to reconstruct the terrain before the first building permit.
Motifs extraits
The wording and existing cantonal practice distinguish new builds from conversions/extensions. The special rule for earlier conditions in § 5(2) ABauV/ZH addresses abuse and applies where the ground was altered in view of the planned use, but it does not require historical reconstruction for every new build.