Reddit mentions of The Red Atlas: How the Soviet Union Secretly Mapped the World

If you look closely you can see the shapes of individual buildings, which can be discovered via satellite imagery. Then you have street names and place
names, not terribly difficult to obtain when you have diplomatic staff in the city. There is also hydrographic information about the Potomac such as
depths, flow rate, and width, which was often taken from the official surveys (to say nothing of having a soviet branded survey vessel taking readings
outside the Pentagon's windows). Less obvious from the picture is that they have ascertained the building material, weight limit, and clearance of the
bridges, which could only have been done by boots on the ground.

Here's a larger sample taken from the same scale. Look how much detail went into that. Borrowed from here.

Now picture that all of this information was mapped by the Soviets of nearly the entire world's urban areas- over 2,000, though many have not resurfaced-
and you get a good idea of the wealth of information that they had to work with. In some of the Warsaw Pact countries they had crazy details like
individual trees and the distance between them listed.

These maps are fascinating and a little unsettling. They have a lot of details left out of official published maps, like military installations, the names and products of factories,
mountain passes and what time of the year they were passable, police stations, even subway line stops and if the lines were electric or not. What does that mean? The maps could be
used for conventional air strikes bombardments, and troop movements, but that doesn't account for the civilian infrastructure like mass transit- they must have been occupation maps as
well. They knew which bridges their tanks could cross, which rivers their ships could navigate, where the vast majority of our military and government buildings were, the various heights
of neighborhoods to help troops unfamiliar with the area... And not just the US, either. Most countries. On top of that, the maps were regularly updated. Think of the resources needed
to handle all of that.

While no one is sure just how many maps there are and of what areas, a lot surfaced in the Baltics following the collapse of the Soviet Union.
This article from Wired is a fascinating read. You can now buy originals and reproductions from ebay shops based in Latvia and
Lithuania as well as vendors who likely purchased from those guys. Here is a large scale map of my hometown of Dallas, TX. Incidentally, if anyone
can find a copy of the 1:25,000 map that supposedly exists I'd love to see it. It would look very cool on my wall. It's unnerving and beautiful all at once.

Further reading: Red Atlas: How the Soviet Union Secretly Mapped the World
This book was recently released and I finished it yesterday. It's more of a technical analysis, there still isn't really any information about the how and the official why.
I thought it was fascinating. It goes into the detail, the errors made, the cultural assumptions made that didn't translate well, etc. You can tell a lot about a country by
how they draw and label yours.

Thanks for reading! Would love to see any additional info on this in the replies. I'm so amazed that these maps exist.