There are many reasons to like overland travel, and many more not to like it. There are also many versions of these overland routes. Sufficed to say, taking no planes is one of the rules. Cars, bikes, buses, boats, trains and feet are all good.
A famous route to and from Europe/Asia. The common railway route links Moscow with Vladivostok and Beijing. Couple that it in with the Trans-Mongolian routes and Korean and you have many options. A one way ticket is likely to cost around $350 USD, but this is basically non stop. The way to do the route really, is to hop on and off en route. This will boost the price up to scary proportions, not to mention add to your Russian visa headache!
This ancient trading route is possibly the most famous overland travel route. In actual fact there's more than one route. So you might have to make up your mind which one to take. Europe, Asia, the Middle East, SEA. They are all linked. Have a look to the map on the right to get an idea. Learning your routes history is going to make it more interesting. A classic route on the silk road is Marco Polo's route, or Alexander the Great.
A modern day overlanders challenge. These days many people head off from either the UK or OZ for work or permanent moves. They make their way through SEA, up to Russia or through Pakistan and Iran into Europe. The hardest part is actually sticking to the overland part. SEA and Australia are not linked and boats are scarce. It is possible though. Likewise for some nationalities visas can be an issue.
A series of hardcore routes give you the option of starting at one end of Africa, and making it overland to the other end. There are plenty of overland companies out there offering to take you. Then again going independent is really going to be an adventure of a life time. Visas, wars, weather, language and unpredictability make the African option a place for boys to become men, and girls to become women.
Like the above, this is not for the faint at heart. There are essentially three routes. Two coastal, and one through the middle. Here, visas, a surprisingly high cost and the odd closed border are the main issues. You know which route I would prefer don't you? Not to be taken lightly.
Overland Route? Yes, aside from South America it's probably the most overland crossed travelers region in the world. Thailand, Cambodia, Laos, Vietnam etc are all linked with relatively easy borders to cross. Visa hassles are low, and there are plenty doing it.
A very long stretch of land. With a problem in the middle. Colombia to Panama overland is to be avoided at all costs. Bad bandit territory has resulted in regular kidnappings, and none that often end well. Apart from Karl Bushby that is. Aside from that hiccup, it's a long journey that can be done with relatively low hassles. Aside, perhaps, from U.S. immigration these days.
An overland route around Australia, possible by train, car & ferry, train, ferry& bus, or simply by car & ferry themselves. The northeastern underdeveloped route is the only challenge other than time. Tackling an overland journey like this is not about the route, but it will be about the journey along the way.
No way! These maps are just examples. Overland travel often changes as you go along. Visas, restrictions, wars, events, weather and a host of other things can change your route.
A common misconception is that overland travel is a lot more expensive than taking a flight. Well, you need to look at a couple of things here. What type of traveler are you? If you like expensive hotels, then yes it will be more expensive.
If you were to take a flight to every country in the Americas route, and compare it to going overland, and visit the same places en route. Then overland travel wins big time. If you just take a flight from Argentina to Canada, well then ...
I did a budget once for a realistic RTW flight vs an RTW overland once and the flight came out cheaper, but taking into account the places en route, overland won again.
This can be done the hard way or the easy way. The easy way is just to head off. But be warned if you haven't done your research first, you might end up having to travel back a very long way to re-route. So yes, I say research your route first.
Sit down with a map of the world or region then draw some lines. Once you know the countries, find out about the visas, and permits. Then look at what borders are closed between countries. Example, Morocco - Algeria, Burma - India.
Once you have the above understood, it becomes easier.