if you want a real mindbender, run it on the post-quake aerial photograph:
bit of a skew to it, just consider it a bonus nav challenge. click through for the big'un (7000px wide!). details yonder, one of the best pictures ever taken, in my opinion.
While the earthquake was devastating, most of the damage was done by the resultant fires. 80 percent of the city's buildings burned down. So it is quite amazing that almost all of that April 1906 grid survives today. In 1906 San Francisco was the largest city in the western US. It's probably worth it to do some reading before competing.