Famous across China (although a little overhyped if we're being honest), Old Dragon Head, 4km south of Shanhaiguan, is where the Great Wall meets the sea. It's photogenic for sure, but bear in mind that what you see now was reconstructed in the late 1980s – the original wall crumbled away long ago. Bus 25 (¥2) goes here from Shanhaiguan’s South Gate.
To walk along the beach for free, and bag the famous wall-meets-sea photo, you can bypass the ticketed area altogether; take the first left ahead of where the bus drops you off, and follow the road for around 300m, eventually walking through the Great Wall itself via a narrow traffic tunnel that pops you out beside the beach. The beach is a decent strip of sand, though you'll have to try to ignore the huge shipping port that looms large in the distance.