It does make one wonder how older maps were so accurate. Medieval cartography would certainly be an interesting subject to study.
I've been using a LuniSolar calendar in my personal life for about 2 years, and have found it to be a nice change in pace.
Medieval cartographers were definitely more esteemed and important than cartographers today. Maps were very valuable which is why we have so many.
I've read articles and watched a few short documentary on it, but generally they weren't allowed to share their national, or trade company secrects.
I do know telescopes and calculus really improved things. With greaterbaccuracy, instead of waiting for rare events, far more common events could be used.
The unisolar calendar looks interesting. I have a free one O got from a local pharmacy this year.