https://en.wikipedia.org/wiki/Border
List of countries and territories by land borders
List of countries and territories by maritime boundaries
List of land borders with dates of establishment
Separation barrier
https://en.wikipedia.org/wiki/Separation_barrier
Border control
https://en.wikipedia.org/wiki/Border_control
Border guard
"Guardia di Finanza - Cinofili (K9) - Malpensa" by Massimiliano Mariani - Own work. Licensed under CC BY-SA 2.5 it via Commons - https://commons.wikimedia.org/wiki/File:Guardia_di_Finanza_-_Cinofili_(K9)_-_Malpensa.JPG#/media/File:Guardia_di_Finanza_-_Cinofili_(K9)_-_Malpensa.JPG