There are places you return to in your dreams, a great-aunt’s cottage or primary school canteen, repurposed by your subconscious as a location for flirtation, horror or something dental. Since I first learned about it in the early 2000s, when I lived down the road, one of mine has been the Mole Man’s house. He was William Lyttle, a civil engineer who liked to dig. In his Hackney home he dug and dug, burrowing and nibbling through the earth, hollowing out a web of tunnels and caves, some 26ft deep, some hung or strewn with objects, like bath tubs, old fires and TV sets. There was also a boat down there, and the wrecks of three Renault 4 cars. In 2006, when Lyttle was 75 and more than 40 years into his dig, the Guardian reported that he was being evicted from his own house because (said a council surveyor, ominously), “There has been movement in the ground.” Lyttle said he was simply making “home improvements”, and, “I thought I’d try for a bit of a wine cellar and found a taste for the thing.” Besides, “Tunnelling is something that should be talked about without panicking.” He was talking in what is now recognised to be the language of the property developer or oligarch, whose houses are only complete once their builders have hit the water table. Back then, though, Lyttle was moved into a top-floor flat to avoid more tunnels. He died there in 2010, but not before burrowing through the brick wall and becoming a kind of folk antihero to many. I was on holiday in France last week, where I sat in the shade and read about the opening of City in Nevada, a monumental piece of land art, more than a mile and a half long, that has taken Michael Heizer 50 years to complete in sand and cement. In that heat and in my mood the weight of a project of that scale, which takes a lifetime felt oppressive and darkly magical. I was staying near the Palais Ideal, a castle built at the turn of the 20th century by Joseph Cheval, a postman, from pebbles he collected on his rounds. Though Cheval’s neighbours at the time thought he was mad, their children live off his legacy today: its abstract architecture is a national monument. Not so the Mole Man’s house. Hackney council filled the tunnels with concrete and left it standing derelict for years until, at auction in 2012, it was bought by the artist Sue Webster. When, this weekend, I posted about my Mole Man dreams on Instagram, Webster invited me round for tea. I got on the bus. On my way, I wondered what it was about this story that made it so ripe for obsession. Is it just the mystery? The idea that there was something down there that Lyttle was searching for? A psychiatrist said tunnel digging can be interpreted as “a desire to return to the security of the mother’s womb” and yes, there’s the image of him scrabbling through the dirt as if back in time, an unquiet quest. As I walked through the modern glamour of De Beauvoir in summer I saw hoardings behind which basement digs were under way, and half a thought about social cleansing and the limits of a home flashed through my mind. But as I passed the rusted green gate and Webster waved, I realised my obsession, today anyway, is rooted in the ways artists carry on making things that do nothing, or digging down to nowhere, just because that is what they must do and they have no choice but to. From the outside the house looks remarkably similar to how it did in Lyttle’s day. With architect David Adjaye, Webster tried to restore as much of it as possible – steps end abruptly mid-air, concrete made with rocks and pipes jut across the ruins. Inside, though, is a vast open-plan space of wood and concrete made precisely to suit Webster’s needs: one large bed, one large studio, with a wall tall enough to contain her current work, a “crime scene” of her life. Still, after five years of expensive renovations, she’s dealing with the council’s planning permission people, and there’s the sense that, like the artist in Nevada or Lyttle himself, this must be their art, a lifetime of emails. Webster became famous for work made with rubbish – a light shines on a heap of trash to reveal a refined silhouette of the artist – and this house, unstable, with its grime and ghosts and skiploads of rubble, is its perfect continuation. It’s comfortably odd, too, raw and bunker-ish, and it shows the value of, the need for, the privilege of, even, eccentricity and artists. Asked, on his eviction, why he dug, Lyttle said he didn’t know. Was he an artist? An architect? A treasure-hunter? “I don’t mind the title of inventor,” he said. “Inventing things that don’t work is a brilliant thing, you know. People are asking you what the big secret is. And you know what? There isn’t one.”