My first housing block is the one with administrative city inside. Second is an elite housing block built around Large Palace. It doesn't have many houses but it turned out to be enough to meet the mission goal. My second worker block is built around Grand Pagoda.
It's a shame that monuments don't generate any desirability. They can look really pretty like those two in this mission.
Forts in a S-W corner are kind of a weak spot as they can't be protected by walls too well and there's a invasion point nearby. Fortunately, repelling an invasion (the only one that launched there) wasn't much of a problem. All of the big invasions (worth 60000 gold on VH) came from the north where my city was prepared better.
The mission is won right before a large Mongol invasion. So beware :)