The Great Wall of China is the only human made construction that can be seen from space. It is hundreds of KMs long and was built to keep out the Mongol invasions.
There is a Mongol joke that it doesn't matter how big a wall you build, it matters who is on the other side to guard... they say this as a joke since they were able to invade 2 times after the wall was built.
BUT... considering that before the wall was built the Mongols could invade at anytime (and did so), the wall did prevent many invasions. The Mongols then had to use superior tactics and not just brute force to succeed. So in fact the wall did help keeping them out since over the 100 years or so they invaded only 2 times rather than what happened in the past which was more like every decade. Forgive me if my history is a bit off. We didn't take a guide here and didn't make a big effort to learn the details this time.
What we do know ---> the wall is amazing. Climbing it and walking along it was wonderful. Seeing it go on and on was something special.
There are a few sections open to the public. There are tours from Beijing that can take you to any sections. The main section and main tourist spot can also be found by taking the bus. The bus costs around 15RMB and goes every 15 minutes back and forth from the city. Takes about 2 hours on the bus.
There are sections which are less touristy also - these are often what is provided on the tours. You can also go on your own, you take a bus to a local town then a mini bus or taxi. The bus cost 15 RMB, but then the mini bus or taxi can cost about 50 RMB a person. The taxi is only advisable if you have 4 people to fill the cab otherwise it is more expensive.
Getting to the places is not hard, it is coming back that is the problem. There are often not enough tourists to get a taxi and so the mini buses want to charge 100 RMB each to get back.
We go lucky, we found some Beijing locals going back to Beijing and they drove us all the way back to the city for 100 total..
Going to the wall the entrance fee is 90 RMB no student price during high season. This ticket is only for THAT specific section of the wall. It is possible to walk to another section (we did try that), but they charge you another 90RMB to cross to another section. So we had to walk all the way back to the original spot to exit the wall.
Walking back, it is possible to get off the wall and go walking thru the paths that the locals use. The walk then takes 30 min and not 2 hours.
Ciao for now...