One of the most surprising items I’ve ever found on a hotel bill was “Wall — £50”. It followed a night in a slightly faded seaside hotel with perhaps the most shockingly beautiful woman I had ever talked into spending a night away with me.

Sadly, what was meant to be a night of passion turned to one of compassion as we sat on the bed emptying the minibar. She sobbed about her rotten ex-boyfriend and how difficult it was to find men who didn’t just want her for her body, and I crossed my legs and nodded with “new man” sympathy. The climax came when she smiled through streaks of mascara, squeezed my hand, and passed out.

“Wall? What wall?” I waved the bill at the concierge. He calmly led us back up to the room to show us a maze of cracks in the plasterwork, stretching far and wide, radiating from behind the bed.

“It’s probably this,” he said, wobbling the headboard slightly, “knocking the wall.” He glanced at my pants-achingly gorgeous companion before giving me that sly smile shared between men that simply says “You lucky dog.”

“Knocking? There was no…” I stopped when I saw the concierge’s look of unalloyed respect — nay, jealousy. The wall wasn’t just a wall. Walls don’t have ears, they have mouths: they speak. This wall was speaking; it was lying but speaking all the same.

It’s one of our great gifts, or curses: the ability to read almost anything into almost anything. Our evolutionary survival depends on our being able to find symbols in the inanimate, to read the signs of danger, or nearby prey, or who might actually put out when you invite them on a dirty weekend.

The concierge was simply doing what we have always done: he found the story he wanted written on an uninterested wall. Throughout history we have constructed walls to define ourselves, our spaces, our defences, reaches, limitations, and to tell the stories of what we have achieved or have the power to do. Walls deter, defend, detain and declaim.

This cracking wall declaimed a fantastic story, with a happy ending. Now we’ve commemorated 20 years since the cracks appeared in that über-symbolisch wall in Berlin, but as the breaking down of symbolic walls goes, this year we could also be celebrating the anniversaries of Pink Floyd’s The Wall (30 years), the Stonewall riots (40 years) and the mother of all symbolic collapsing walls, the one we forgot to remember, Wall Street (80 years).

In fact, from Hiroshima to Dresden, Coventry to the Somme, one of the 20th century’s most defining symbols is a wall teetering on the verge of collapse. Perhaps it was an empire crumbling, and two world wars when the wholesale destruction of walls became routine, but after an era in which they had proved useless as defence and the wall appeared somewhat obsolete, the wall became a potent symbol of old ways, class distinctions and social barriers.

The late 20th century was rife with disassembling divisions, philosophers “deconstructing”, old-school ties and union strangleholds prised apart. From the culture of “open plan” and atriums to the expansionist middle-class habit of “knocking through”, if there was a wall, it was in the way. A world without walls beckoned.

But in architecture the century marked the birth of a new “curtain wall”. Skeletal girder construction meant buildings no longer needed the support of external walls; they could be clad in delicate glass. By the 1960s, the idea that one of our traditional four walls was transparent and no longer defended privacy had become entrenched.

In Joe Orton’s 1965 play Loot, his Inspector Truscott accepts a bribe, saying that it will “go no further than these three walls”. He gets a laugh because he momentarily recognises the setting, the reality that the audience is present and watching. Actors had long referred to a “fourth wall” as the invisible one through which the audience observe, but Orton’s illusory removal of it was a prophecy for our age. Our generation has grown up aware that we are always on show.

We accept, even welcome, the omnipresence of CCTV, or celebrities who are famous for being famous. We stare through the one-way mirrored walls of the Big Brother house with no sense of impropriety. But the danger in breaking walls is breaching our sense of security. Our 24-hour always-on-show transparent fourth wall defines us through our insecurities. We text, blog and tweet in fear of our own solipsistic identity crisis: do I still exist if there’s nobody to watch me? Aren’t we asking, with each wink, nudge and poke, not “Are you still there?” but “Am I still here?”

The truth is, we haven’t broken any walls. We’re still alone, we’re still strangers to our neighbours; we’ve just made an opaque wall more transparent and insidious. We’ve put up a new wall to defend our image, detain our “friends” and declaim, “I blog therefore I am” — the Facebook message wall.

From Banksy to the West Bank, we’re still putting up walls because we can’t resist showing off. And I imagine that’s why I simply winked at the concierge, smiled and handed him my credit card.

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