It's a monument. It stands 202 feet tall and if it fell due west its top would land at the site of the baker's shop in Pudding Lane where the fire began that burned for three days in 1666 and destroyed most of the City of London.
The monument is called The Monument. Like its name, it's elegant and it's simple - if that is not tautology - and it was built in1671.
You can climb it for a fee, up an internal spiral staircase of more than 300 steps. I did so once some years ago for no particular reason and what I remember more than the view from the top - of the Thames and St Paul's and Tower Bridge and all the old familiars - was the dozens of slumped and gasping Americans leaning on the hand rail or flat out on the stairs, defeated by their bulk. I felt the joy of disdain. But these days I'm as fat as they were. The whirligig of time.
I'm sitting now at the nearest pub, also called The Monument. It embodies all that's worst in modern pubbery: with fruit machines and low slung ceilings, sticky tables, giant screens on every wall and shaven headed men with pints of lager watching football.
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I've brought my beer outside, a pint of Greene King IPA, the beer that was my crutch and staff at university, and placed it on a pavement table that proved typical of its kind.
I slid a folded beer mat under one leg to stabilise it and that worked just as well as usual. The spilt beer has run away to the right and formed a little Ganges delta at the table edge before dripping to the pavement.
Every few minutes the Tube station, also named Monument, disgorges another slew of people. The locals stride away with purpose. The tourists gawp and dawdle. They crick their spines and shade their eyes to gaze up at the Monument, which makes many of them sneeze.
Some try to take a selfie that gets the whole thing in, but, even if they place the cellphone on the ground, it seems it can't be done.
The base of The Monument is a square plinth, as tall as half a dozen men. An allegorical carving depicts the city of London as a weak and broken woman, with King Charles the Second coming to her aid - which is just the sort of flattery that worked on monarchs then and works on presidents now.
Above the plinth are decorative carvings - finials? acanthus leaves? - now blackened and eroded by three centuries of rain and city air. And above them rises the massive single column, fluted from top to bottom and built of hand-hewn blocks of limestone. It's a marvellous thing, a visionary bold memorial, that speaks of tribal pride and a refusal to be daunted by misfortune.
The Monument's just round the corner from London Bridge, across which I walked half an hour ago like one of Eliot's crowd of office workers.
A city needs a river and a river needs its bridges and London's many bridges are as good and various as anywhere's. But London Bridge has been defiled. The broad inviting footpaths on its flanks are now blocked off by the sort of concrete defences they put on Britain's beaches to fend off Hitler's tanks.
The enemy now is terrorism. Some months ago, you may recall, Islamist extremists drove a Transit van up the kerb on London Bridge and into innocent pedestrians. The Islamists then leapt out wielding knives and went stabbing in Borough Market. Four people died.
Now, Millwall is a football club based not so far from here whose fans are infamous for violence. And the story goes that when one of the jihadists burst into a pub with knife held high and cried 'This is for Allah', some shaven-headed football-watching lout replied, 'And this is for f*#$**g Millwall', and kicked him in the balls then stamped on his head. I doubt it's true but it's the sort of story any tribe would like to tell itself.
The tank defences on London Bridge are token gestures, a sop to the illusion of security. You can't defend a whole city against terrorism. But you can defy the terrorists.
So rather than pretending to make a place safe with concrete barricades and security announcements on the tube, why not erect a monument to the Blessed Thug of Millwall? No matter that he's mythical. It is always better to defy than to cower. He embodies a refusal to submit.
And 300 years on, how the tourists would flock.