if you approach the foreman, sometimes you can get permisson, in macon we get the old Sanborn fire company maps, pre 1900, and they marked all the outhouses, out buildings, wells, cisterns etc.. we approached a major construction site about doing something and got screamed at. we sat back and waited, and they were going to put a major support on top of an old well. my bud saw the circle of sand, and them looking at it, called them to the fence, and gentlemanly liked handed them a copy of map that showed they were going to run into major problems. they let him in, he probed the well sites out, they dug them out, repacked, and he sold one bottle, just one, for 6 grand, John Ryan blob in cobalt from Columbus. the rare version. it has doubled since. he made about 2 grand more, and we got to hunt a little with detectors. some coins, other neat things. we were lucky on that. many cities had private fire depts through insurance companies, and if you did not have a marker on the door, ar could not pay, you had better have a lot of friends and buckets. remember the movie, although kinda stupid, Gangs of New York, and the fight over who was getting paid to put out fire? go to local library or search on line. treasure trove of info. they put more than bottles in wells, and i will take a good bottle while digging anyday. we are currently helping local county on old downtown sewer system that was done pre 1900 to divert a spring, and boy is it going to be a job and cost this little place a fortune, but it may open us a window of opportunity to hunt 1820 area. all think outside the box, under it , on top, and tear it up!