Better than Toynbee Tiles
City of Pittsburgh - Survey Control System Update Phase I of 1988.
First off, I would love to know what that report cost. But it is pretty amazing and just the summary is full of incredibly wonkish history. The City's "Geodetic Survey and Mapping Division" dates back to 1925 and was set up at the instigation of Frederick Law Olmstead. Supposedly the city of Pittsburgh had "the world's first Global Positioning System (GPS) technology for geodetic control of a city in 1984." You might think all tech/city things were new? Maybe not and maybe we just lost the edge we once had?
But it gets better. The city apparently maintained a "geodetic control system" between 1925 and 1962, and subsequently seems to have lost all institutional memory of said system until the 1980s. The report was part of a 're-discovery' of past work. That work included searching for 895 geodetic control points installed throughout the city earlier in the century.
Can we find any of these geodetic control points today? And what happened after this report came out? What is really amazing is that it is pretty clear Pittsburgh was once on the geography/data cutting edge and somewhere lost its way. I'll go into the past history of Allegheny County and Pittsburgh's historic data infrastructure in the future, but again there was once some cutting edge work here.... most all would be lost either before of coincident with the economic miasma of the 1980s.
Anyways.. we have to find at least one of these. One appendix (staring on page B-2) of that report linked above goes through a list of markers they found, or knew the disposition of.