If I knew what a KML file was, I could tell you :-)
"Keyhole" was our first series of really effective reconsats. "KML" ( a "markup" language like HTML) -- aka "Keyhole Markup Language" -- was developed to manipulate the data from the Keyhole sats. Google supposedly acquired it from a CIA front company...
"Play" with Google Earth for a while... That sidebar on the left is your "KML Catalog" (similar to the ArcGIS Catalog for GIS mapping).
Every time you create a "Push-Pin" Placemark, it's stored in your catalog. If it's checked, the pin itself (and its label) are visible. No matter where on earth you're located, double-clicking on that placemark's name will "fly" you right to that point -- and zoom you right in on the exact view you had when you created it -- including the date and time of the overflight!
BTW, the "clock" ion at top will open up a "time slider" at upper left that will allow you to select between different overflight dates for your location. (You can "time-travel" back into history -- and pick the best [cloud-free] views, etc.)
Have fun! And, if you have questions, FReepMail me...
FRegards,
TXnMA