Wow the Legion of Honor Graves. I am a CRM Archaeologist and my wife works for the city as an architect and I have some stories about the Legion Cemetery. Apparently the city cemetery used to gather all of the unclaimed bodies and use them for medical schools and experiments in tne hospital that became the Veterans Hospital. I worked with several archaeologists who worked on the Legion site. They recovered entire jars of eyes and boxes of limbs from the site. Also many gold rush era folks and one wearing the oldest pair of Levi's. Many interesting artifacts of gold rush SF where recovered at the site.
As for the arch that can be seen driving up to the Legion from Clement that is an old Chinese grave marker. Many markers that remained unclaimed where heaved over the cliff and fragments can be found to this day if you hike the trails below the Legion.
An interesting and significant site in SF history. Another interesting one is the old Lone Mountain Cemetery lots of photos of that on the SFPL website under digitized images.