The actual border is just marked by a concrete block, and you could walk to the north of it wasn't for the fact you would probably be shot on the way. You can feel the tension as the soldiers eyeball each other just a few feet apart. 

To enter the DMZ. First you have to be briefed by US soldiers and sign a waver that if you get shot by North Korea you won't hold the government responsible. Then you are taken by bus, through the tank traps and mine fields up to the row of buildings which mark the border. 

You can then gaze into the North and watch the guards observing you. You can look at the propaganda village of Gijeong-dong with its massive flag and its streets empty of people. And you can see the tree where two U.S. Soldiers were hacked to death while trying to trim a tree in 1968. 

You even walk into the North inside the building which straddles the cease fire line and see where all major talks between the North and South take place. 

There are occasional incidents all the time, the most recent last month when South Korean activists sent up balloons with peace messages only to have them spot down by the guards of the North. 

Finished with a look at one of the tunnels North Korea tried digging under the line as a possible invasion route