How to build a road on either an uphill or downhill grade that might last 1000 years

https://www.zmescience.com/science/how-roman-roads-were-built/


scroll down to
“How Roman roads were made”

While your mind might first think
“Drainage, Drainage, Drainage”
now refocus on
Freeze/Thaw Expand/Contract
over thousands of cycles

You might object:
Romans had no idea about concrete !

No, no, no - their concrete was actually SUPERIOR to modern stuff
( made from unique volcanic ash )