One of the more novel Achievements / Trophies in Just Cause 3 demands Rico stand on the highest peak in Medici on-foot.
It's easy to do, but not so easy to find, as there is no indication on the map. Here's how to find the highest spot on the map.
The highest point is located in the Insula Striate region (the biggest one) in the Montana province.
I've placed a waypoint at its location. The coordinates are N 40 48.106 E 5 43.230. It can be hard to pinpoint the exact coordinates with a controller, so roughly finding them will be close enough -- you won't miss the giant mountain!
You'll see the snowy mountain from over 10km away. Head towards what appears to be the highest point. The easiest method is by helicopter, but you can be more ambitious with a jet or wingsuit.
I approached from the south-west, but it's easy to spot the highest point from any direction once you've entered Montana.
Use the helicopter to slowly move in towards the tallest mountain ridge and you'll see a small shrine -- that's where you want to go. You could also jump and wingsuit / parachute there, but the shrine might not pop-in before you land.
There it is! The highest point of Medici.Walk to about here -- just before the steps -- and the Achievement / Trophy will unlock.
Now you know what you want to do: Jump off and try and beat our Wingsuit record!