These are strictly speaking not battlemaps - but if you are running a ‘real world’ type game, take a look at the Library of Congress.

I’m running an Old West game. There have been battle maps from here (saloons, ranches, etc) that I have picked up – but the area maps were tough until I stumbled onto using the LOC. There are some INCREDIBLY cool things out there.

For example, this is the survey map (as of 1863) of the entire US – fairly detailed (also HUGE if you get the really detailed version):

https://www.loc.gov/resource/g3701b.ct003951/

My team was originally based near St. Joe, Missouri – and there are actually a series of pictures out there that somebody got up in a hot air balloon and painted (so it is a literal aerial view from the time period). I use this as a the splash page for my online game.

https://www.loc.gov/resource/g4164s.pm004370/

It’s free (or at least if you a US Citizen, your tax dollars paid for it) – might as well make use of it.