Image: Jan S. Krogh National borders are often a touchy subject involving a combustible mix of politics, patriotism and geography. Some borders are complex because of they're based on natural rivers that change course over the period of many years, and some are complex because they're political creations to solve territorial disputes. Take, for example, enclaves and exclaves. These are territories that are entirely surrounded by another. You all already know the most famous example: the Vatican City is a...