Where a wall goes in Antioch changes how tall it can be. The city limits any wall, fence or hedge in the required front yard to 36 inches, and it has to stay out of the public right-of-way unless the city's Director of Public Works issues an encroachment permit. On a corner lot, a side yard fence built with a retaining wall facing the street sits at least three feet back from that wall.
On a sloped lot, the city measures side and rear wall height from the grade at the property line, and where the ground differs on each side it may be measured from the higher side. So on uneven ground, I work out with you which side the height counts from before we pick a number.
We're based in Antioch and build in the cities around it, from Concord and Walnut Creek out to Brentwood and Rio Vista. Outside Antioch, I check the wall rules for your address before we plan anything, and if you're not sure we cover you, call and ask.