Warsaw, the city copied from paintings.

01 A square that is not old and does not hide it

On the Market Square there are gables, mouldings, sash windows and cobbles that sound old underfoot. None of it is more than eighty years old. Around eighty-five per cent of the historic centre was destroyed in the mid-twentieth century, and what you walk today was raised from nothing from 1945 onwards, with the bulk of the work finished before 1955 and finishing touches running into the 1980s.

What is interesting is not the reconstruction itself —other cities have been rebuilt— but that Warsaw did not disguise it. On 2 September 1980 UNESCO added the old town to the World Heritage list with an unusual formula: as an outstanding example of a near-total reconstruction of a span of history covering the thirteenth to the twentieth century. In other words, the old building was not what got protected. The act of remaking it was.

02 The painter who unknowingly left the drawings

Here comes the piece that makes this story singular. Between 1767 and 1780 the Venetian Bernardo Bellotto —nephew of Canaletto, and known in Poland by his uncle's name— worked as court painter to King Stanisław August Poniatowski. His commission was to paint the city, and he painted it with almost topographic care: cornices, railings, signs, the number of openings on each facade.

Twenty-two of those city views survived intact, and the city's preservation department used them as the main reference material for the reconstruction. Since 1984 they have hung together in a room of the royal castle named after the painter's uncle. Seeing the paintings after walking the streets is the experience that best explains this city: first you walk the copy, then you look at the original.

03 What a painting cannot tell you

It is worth saying what the romantic version of this story tends to leave out. Bellotto was a painter, not a surveyor: he composed his views, adjusted proportions and arranged the framing so the scene would work as a picture. His canvases give you the relative height of a tower and the rhythm of a facade, but not a level or a construction section.

Nor was the reconstruction a photocopy. The external appearance of the streets was remade to their eighteenth-century state, but inside, the buildings were reorganised to twentieth-century standards: fewer dwellings per block, more open courtyards, modern services. What was copied is the skin. The city behind it is another one, and that is also part of what there is to understand while walking it.

04 The other Warsaw, the one that copied nobody

The old town covers a few blocks. Around it lies a capital of almost 1.9 million people that was not rebuilt by looking at any painting, and there is the tension that makes the whole thing interesting. A kilometre south of the square stands the Palace of Culture and Science, two hundred and thirty-seven metres of stone and pinnacles completed in the 1950s, for a long time the tallest building in the country.

And around it, over the past two decades, a cluster of glass towers has grown that now forms the tallest skyline in this part of Europe. The result is a disconcerting silhouette from the river: skyscrapers, a 1950s stone tower, and to the north a handful of eighteenth-century red roofs remade in the twentieth.

That mixture unsettles anyone looking for a coherent capital, and it is exactly what defines this one. Warsaw has no continuous fabric that aged layer upon layer: it has fragments, each with a very definite date. The city reads in blocks, not in transitions.

05 What Warsaw leaves you

What stays with you is a question almost no city forces you to ask: what makes a place authentic. If you cross the Market Square knowing nothing, it is a handsome and slightly small European old town. If you know what you know by the time you get here, it is something else: the result of a collective decision to remake what was lost rather than replace it with something new.

Warsaw does not ask you to believe it is old. It shows you the paintings it came out of and lets you decide. Few cities offer that transparency, and it is why, on leaving, you do not remember a particular facade but the odd sensation of having visited a city and its documentation at the same time.