Obviously, I've been spending a lot of time looking at the UCLA Library Digital Collections.

Here's an interesting set to ponder:

Today: http://maps.google.com/maps?q=main+st+and+alameda+st&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&hq=&hnear=N+Alameda+St+%26+N+Main+St,+Los+Angeles,+CA+90012&gl=us&ei=uYEGTd3iGo-msQOs8enzBw&sa=X&oi=geocode_result&ct=title&resnum=1&ved=0CBMQ8gEwAA

1877, "Lands of the Los Angeles City Water Company": http://digital2.library.ucla.edu/viewItem.do?ark=21198/zz0015zzqq