| @dino: It is possible to visit all of the countries (expect islands, of course) in North and South America in a single path with no repeats (visiting each country only once). And as biner has demonstrated it is possible to do that in Europe, again with the obvious exceptions for the islands and countries that only border one other country (Denmark, Monaco, Portugal, San Marino, and Vatican City), unless you start or end the path in one of those countries. But in Asia the situation is impossible (consider the countries on the Arabian peninsula, for instance). In south Asia there's a problem in the Malaysia/Indonesia region, not to mention you can't include both Nepal and Bhutan (because their only border countries are India and China), nor Mongolia and North Korea (because their only border countries are Russia and China) in the same circuit unless you start or end there. |
Countries of Europe 
Countries of Africa 
Countries of Asia
