The Cape Horn monument—so much history here it's spectacular to be in the same waters that so many explorers sailed before. The waters around the Cape are particularly hazardous, owing to strong winds, large waves, strong currents, and icebergs; these dangers have made it notorious as a sailors' graveyard. However for the lucky few who actually made it around the horn alive, they called it "bending the horn."
You can visit Cape Horn and see the lighthouse, monument, souvenir shop, and meet the one family who lives there. But you can only get there by boat. Australis Cruceros will take you to Cape Horn as part of a longer cruise through Patagonia. Be aware the often fickle weather and sea around Cape Horn must cooperate for you, as you are restricted to land if the wind is too strong.