Shanhaiguan has its own train-station. It's only a few minutes by train from Qinhuangdao train-station. A direct train from Beijing takes 3 hours.
At Shanhaiguan, the Great Wall juts out into the sea. This part of the wall is known as the "Old Dragon's Head".
Further inland, The pass of Shanhaiguan is to be found. The pass of Shanhaiguan is a square, with a perimeter of around 4 kilometers long. The walls reach the heigh of 14 meters, and are 7 meters thick. The pass's east, south and north side is surrounded by a moat of 8 feet deep and 17 feet wide. There are drawbridges to get over the moat, and in the middle of the pass stands a tall bell tower.
All four sides of Shanhaiguan had a gate: Zhendong (East), Yinun (West), Mangyang (South), and Weiyuan (North). Due to disrepair over the centuries, only Zhendong gate still remains today. Zhendong Gate is the most important gate in Shanhaiguan due to its position, which faces outside the pass. On the gate hangs the board, written on it "First Pass Under the Heaven."
Even further inland, there's a small park near another section of the wall. Here, the wall can be seen snaking it's way over the hills. It is possible to take a chairlift/cablecar to get a better view, or if you're feeling fit, you can walk up a steep section of the wall.
There's also a museum dedicated to the Great wall in the centre of Shanhaiguan.
Much of Shanhaiguan has been extensively restored in the 80s.
Currently much of the "old" town is being completely reconstructed. Quite a few entire city blocks are being remade into a faux-old Chinese city that, in fact, promises to be quite nice when construction is complete.
There is a nice restaurant in the centre where the wall is plastered with pictures of foreign customers who have visited the restaurant. The owner will even offer to take a picture of himself with you if you're lucky. At least one restaurant near the Dragon's Head has been known to overcharge.