Hello. 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, 2-3 story buildings are to be mapped on the same way.
Best regards and keep mapping