The Eiffel tower surrounded by trees
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The Peculiar Relationship Between City Trees and Medieval Battle

Thank war and leisure for today's urban canopies

TODAY, EUROPEAN CITIES ARE unthinkable without their tree-lined streets: their boulevards, avenues and malls. Those three words synonymous with urban trees tell us when and why European cities got their canopies.

Boulevard derives from the Dutch word bolwerk and the Italian baluardo, both meaning bulwark. The introduction of trees into cities was tied up with military technology. Advances in siege gunnery forced military engineers in Antwerp, Amsterdam and Strasburg from the 1570s to defend cities with massive mounded earthworks instead of walls. Other European cities – including Lucca, Gdansk, Vienna and Hamburg – adopted the technique, and planted avenues of trees along the length of the earthworks to prevent erosion. The by-product of military engineering was to create agreeable allées along the walls for promenading in times of peace. The double-planted allée was inherited from the then-fashionable Italian garden design.

In Paris, the widest section of earthen ramparts defending the city was known as the Grand Boulevart, a corruption of the Dutch word. In 1670, in an act symbolising France’s military invincibility, Louis XIV had the ramparts of Paris pulled down. Or rather they were cut down to become raised carriageways 60 feet wide with two rows of elms on either side, flanked by another 20-foot wide allée for pedestrian promenading alongside. They were nicknamed les Boulevards and became some of the most sought-after residential districts in Paris.

City walls and trees were connected in other ways. The Italian game pallamaglio – known as le jeu du mail or palmail in France and pall mall in England – became popular at the same time that city walls were getting a green makeover. The game, much like croquet, was played by the upper classes on lawns surrounded by allées on the periphery of cities. The association of tree-lined spaces with ball games is why we still talk of ‘bowling alleys’, which comes from the French allée. Beautiful sylvian malls appeared alongside the walls of Paris in the 1590s; they were copied in Dutch cities soon after. Berlin got its version, Unter den Linden (‘under the lime trees’) in 1647, a kilometre-long former hunting trail running through sandy fields outside the city walls, planted with parallel rows of 1,000 limes and 1,000 nut trees. Pall Mall and the Mall on the western outskirts London date from the same time, when kings and nobles played pall mall under the shade of trees far from the throbbing metropolis. Such malls were also used as bowling allées and archery ranges.

Another Italian fashion – promenading in carriages along the Corso outside Florence on the banks of the Arno – caught on as well. Nostalgic for the Corso, Marie de Medici, the Italian wife of the French king Henry IV, had the Cours-la-Reine constructed in 1616, a wide carriage-way with four parallel lines of elms alongside the Seine on the edge of Paris. The Paseo del Prado was laid out in Madrid in the 1650s as a fashionable boulevard in imitation of the French cours. The word ‘avenue’ originated from the French avenir – to approach. Avenues were planted on the approaches to Paris in the 17th century, creating grand entry routes into the capital reminiscent of landscaped hunting parks and the formal drives leading to Italian country houses. The most famous avenue in the world, the Champs Élysées, began life as the Avenue des Tuileries, a suburban approach road lined with elms, horse chestnuts and planes running through fields and market gardens.

Boulevards and avenues are now the most characteristic sites of city trees the world over. They began life in Paris in the 17th century much like city parks – as settings on the edge of town for the exclusive leisure of courtly elites whose wealth and world views derived from the countryside. Note that it was on the periphery of cities. Only in Amsterdam and other Dutch towns were trees incorporated into the heart of the city. In 1641 John Evelyn described Amsterdam as ‘appearing like a city in a forest’; ‘nothing can be more beautiful’, he added, than the sight of uniform houses facing canals fringed with limes; it was a ‘ravishing prospect’. The effect was remarkable because it was so new; a French writer said that he could not tell whether Amsterdam was a city in a forest or a forest in a city. It resembled a characteristic southeast Asian city in that respect.

Trees were easier to integrate into new cities, particularly in America. There, colonial cities were reconceived as combining the best of rural and urban, avoiding the mistakes of European urbanisation. Writing in 1748, the Swedish professor Peter Kalm extolled the street trees of downtown Manhattan, commenting that the beautiful appearance, scents and shade of sycamores (Plantanus occidentalis), black locusts, limes and elms made it ‘extremely pleasant to walk in the town, for it seemed quite like a garden’. These New York trees gave home not only to a large number of birds, but to ‘very clamorous’ frogs: at night ‘they frequently make such a noise, that it is difficult for a person to make himself heard’. Loved by the people, trees were treated with suspicion by the city’s Common Council, which decided to remove them in 1791 because they were a traffic nuisance.

Nothing can be more beautiful than the sight of uniform houses facing canals fringed with limes; it was a ‘ravishing prospect’.

By the mid-19th century, Savannah, Georgia, was known as the ‘Forest City’ because it was lavishly embowered with evergreen oaks and chinberry trees, the legacy of its colonial and post-revolutionary sylvian proclivities. Street trees were integrated into Savannah from its foundation in 1733. As a city ordinance had it: ‘Experience has fully proved that great advantages are derived to the Inhabitants of the City from trees being planted in the streets and squares, from the shade they afford, the heat of a very sultry climate is lessened … Council being desirous that the Inhabitants should meet every advantage that Trees planted in our streets and squares can afford, have resolved to extend its protection to all trees standing at this time in our streets, lanes, squares, or which may be hereafter planted either at the public expense or by Individual.’ A visitor to Philadelphia basked in the ‘freshness and purity’ of the city afforded by the long avenues bordered with Lombardy poplars and other species. President John Quincy Adams had elms planted along Pennsylvania Avenue in the 1820s.

Back in Europe, Amsterdam and Paris set fresh standards of urban beauty. As cities expanded, they enfolded suburban boulevards, malls and avenues – such as the Mall in London, the Champs Élysées in Paris, the Prado in Madrid and the Unter den Linden in Berlin – into their fabric. Places that had been peripheral to cities became their focal points, with trees bequeathing them their ceremonial majesty. Trees went from being amenities for aristocratic recreation to statements of power: the Unter den Linden is anchored by the Brandenburg Gate; the Mall (named after a game) by Buckingham Palace; the Champs Élysées by the Arc de Triomphe and the Place de la Concorde. Avenues create vistas that direct the eye to monuments and key edifices; they form landscapes of order. Trees made the formal avenues of modern cities resemble, as Lewis Mumford wrote, parade grounds.

They were an architectural embellishment, sought after by the well-off to soften the harsh edges of the city and impart the grandeur of their country estates to the urban environment. Leicester Square in London became the first urban plaza in Europe to be planted with ‘walks’ of neatly lined trees in the 1660s. By the end of the 18th century, London’s fashionable squares were thick with trees taller than the surrounding houses. When new streets were created in the wake of expansion or were carved into the existing city, at least in the glitzier districts, trees became an, if not the, essential aspect of their design in places like Paris, Toulouse, Lyon and London. In the wake of the Napoleonic conquest of Europe, boulevards were introduced under French influence across the continent, in cities such as Brussels, Turin and Düsseldorf.

But it was the rebuilding of Paris by Haussmann in the 1850s that seared boulevards, avenues and squares (places) into the imagination of city planners. Haussmann cut long, straight, broad boulevards into the heart of the metropolis, providing ample room for the 600,000 trees he planted in the capital, a place that had lacked a canopy when it was a rabbit warren of cramped medieval streets. Framed against buildings and planted along straight streets, trees created instant beauty.

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Paris became the modern template of how a city should look and feel. From Haussmann’s remaking of Paris onwards, trees became indispensable in the urban landscape. Paris’s boulevards inspired public authorities in American cities to soften and beautify the geometrical regularity of the grid system. Commonwealth Avenue Mall in Boston, for instance, was planted with a quadruple row of elms, zelkovas, maples and green ashes in the 1880s, transforming a residential street into a Parisian-style grand boulevard. In the same decade, Washington DC’s avenues were planted out with pin oaks, elms and limes.

Trees came marching into town. They were planted in central boulevards and suburban avenues; they adorned the new municipal parks of the late 19th century; and they became the unmistakable feature of urban cemeteries. When Japan began to modernise after the Meiji Restoration in 1868, stately ornamental trees became a feature of city roadsides. European-style buildings on Ginza Street in Tokyo were complemented with black pine, cherry, maple and black locust. By the eve of the Second World War there were over 270,000 street trees in Tokyo, predominately the London plane and the magnificent gingko biloba, most either planted since the 1870s or replanted after the Great Kanto Earthquake (1923). In an age of intense urbanisation, treescapes had become one of the leading signifiers not only of modernity, but of global prestige. After the reunification of Italy and the restoration of Rome as the national capital, trees were planted throughout a city which had been notably ungreen. The characteristic tree of Rome – the stone pine – was chosen because it had strong associations with ancient Rome. Pines and cypresses, so redolent of a lost or imagined past, were used to showcase archaeological monuments which had previously been barren; holm oaks, reminiscent of the Italian countryside and Renaissance gardens, graced public squares. The Italian conquest of Libya in 1911 resulted in a massive planting of palms in Italian cities: the street tree was an everlasting reminder of imperial triumph.

One of the most delicious urban canopies you can experience is that which turns the streets of what was once the French Concession in Shanghai into cool green tunnels. They were planted from 1887 to give the Chinese city the feel of a Parisian street. They are a reminder that the arboreal greening of cities was an imperial project, conducted in Australasia, Africa, Asia and the Americas. When the British planned New Delhi in 1912 the unmistakable hallmark of modernity and imperial control was the canopy. ‘Trees will be everywhere,’ stated the report of the planning committee, ‘in every garden however small it be, and along the side of every roadway, and Imperial Delhi will be in the main a sea of foliage. It may be called a city, but it is going to be quite different from any city that the world has known.’

Not only were trees the central feature of the new imperial capital, but over 1,000 acres of the Central Ridge were reforested as a topographical feature emphasising the sylvian perfection of the new capital. Observed from the Ridge, New Delhi is indeed lost in its sea of foliage, true to the intentions of its designers. From the right vantage point, the domes of the Rashtrapati Bhavan – India’s presidential palace, formerly Viceroy’s House – and other government buildings poke out of an immense, uninterrupted emerald canopy. The administrative city – with its geometric pattern of shaded avenues – anticipated new town deign and suburban developments throughout the 20th century. Readily apparent is the connection between power and greenery. Look at satellite images of Delhi and the greenness of New Delhi stands out from the monolithic grey of the rest of the megacity: like suburban arcadias all over world, the privilege of living in an urban forest is reserved for the wealthy.

This excerpt is taken from Urban Jungle: The History and Future of Nature in the City by Ben Wilson. Copyright © 2023 by Ben Wilson. Published by arrangement with Doubleday, an imprint of The Knopf Doubleday Group, a division of Penguin Random House LLC.


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Ben Wilson is the author of six previous books, including Metropolis; What Price Liberty? (for which he received the Somerset Maugham Award); and the Sunday Times bestseller Empire of the Deep: The Rise and Fall of the British Navy.