i work construction in SF and have come across lots of bottles and artifacts over the years...many parts of the city are built on fill from the 1800s.pretty exciting but most people never get to enter these areas.most construction sites are gaurded and highly off limits.
i ve spent alot of time walkin the tracks here in cali. and i ve found a few cool bottles..theres alot of history on those old rail lines.look for any turn a rounds where the lines end ,they used to dump there trash around there..