How about adding colored map markers that you can quickly set down and remove.
you know how when you are scanning your area for your next target. and you would like to tag a couple of islands to compare locations, resources, and size.

Kal Gordon

While they aren't visible on the map, there is already a way to save specific locations and quickly move between them.
If you find a location on the map that you would like to save, simply click the button I have put a red box around on that screenshot. You can then assign a name to that set of coordinates. When you want to revisit that location, you simply click the little down arrow to the right of the coordinates, and it will show a list of your saved locations. Clicking on the name of a saved location will instantly move you to that location. Was that along the lines of what you were thinking, or were you after a marker that showed up on the map itself?
that does help a bit.
but the coloured map flags. like when you reserve a city? but a different colour and shape. so you can visually see it when scrolling.


Stickies in a webpage is nice, especially since say other data values are sorta irrelevant for such, leaving temporary works within reasonable progress, but they would be stickies most treated as and most do not work once say page is closed.