If you're running a game on Roll20, Google Earth Pro is an excellent resource for generating battlemap base layers. It has historical imagery, but the satellite quality wasn't great in our era of interest. The modern stuff typically shows greater industrial development and urban sprawl than would have been present in the Eastern Europe of the late '90s, but it works well enough for most purposes.
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linked example image - it's too big to embed in a gentlemanly fashion)
- C.