Thanks for mapping on this project.
Keep an eye on complex buildings. Especial the high rise (multi story) buildings and buildings which shows their side views  as well. Check this footage how to map these buildings 
https://www.youtube.com/watch?v=dsfUcslLtVc
https://drive.google.com/file/d/13RTwH7sChRWrG5bIjysF2ripBgh3F5l4/view?usp=sharing 

Lower buildings, showing theire sidewalls as well can mapped on the same way by moving the mapped roofline to the groundplan.

PLease square also all rectangular buildings with  the Q key while selected.
Best regards and keep mapping
