They found a DUNGEON. Would this story have gone semi-viral under any other name?
Not a basement, mind you, a dungeon. Would a secret cellar or crawlspace be "amazing"? And by that hoary name, older by any reason than the Victorian building, they invoke all that goes with it - torture and skeletons and exploration and adventure. Even if there's no sign of hobgoblins, only hooligans.
The steam-tunnel legends that circulated in the early days of the roleplaying hobby betray the desire to transform the surplus space of industrial civilization into something haunted, magical. Even though this photo essayist doesn't descend into full confabulation as does the Ted the Caver website, you can hardly fault someone for wishing to open that trapdoor and hear the grunting of pig-headed mutants far, far below ... or the scurrying of rats, down the twisting stair to a bone-littered cavern, millennia of cannibal rites and madness.