This made me wonder...are (most) of the (undisputed) borders of the world actually stored somewhere? Or are some stones and posts still the "official" borders?
In the UK (technically Great Britain in this context) at least, there is an open dataset available from the national mapping authority (Ordnance Survey), which is called boundary lines. It contains all of the different boundary lines and borders of local authorities, parliamentary constituencies, regions, nations etc. This is all geo referenced against the OSGB coordinate system. I could see interesting challenges in…
The white area being roads and non-registered land (mainly stuff that hasn't sold for decades and roads).
It's great, I can find a unique owner for any bit of field I have a question about, the size of the plot, etc.
The downside is that to get a copy of the actual entry in the register (to see who owns it and any covenants on the property there are), you have to pay £3. The entire process is digital and automated, IMO it should be free, but I suppose it's not a terrible price.