The 1889 Universal Exposition in Paris. (Library of Congress)

Steven Levingston is nonfiction book editor of The Washington Post and the author of “Little Demon in the City of Light: A True Story of Murder and Mesmerism in Belle Époque Paris.”

Pop the bubbly. It’s time to toast the 125th birthday of the Eiffel Tower, that iron, lattice-work marvel that scholar Roger Shattuck called “the first monument of modernism.” Shooting about 1,000 feet into the sky from the Champ de Mars, the tower stands as a totem of modern Paris, its beauty, romance and joie de vivre.

The era that gave birth to the tower, the Belle Époque, roughly from 1871 to the start of World War I in 1914, is typically portrayed as a period of champagne bubbles, men in top hats and monocles, and carefree strolls along the boulevards. But along with the gaiety came darkness: Doubt, fear and violence also stalked Parisians. The Belle Époque was largely a creation of nostalgia: Those who survived the war looked longingly over their shoulders and remembered a golden era before the carnage. As historian Barbara Tuchmanobserved, “It was not a time exclusively of confidence, innocence, comfort, stability, security and peace.”

From its very beginnings, the Eiffel Tower reflected this unease within French society. As it rose from the earth over two years, platform by platform, to its full height on March 31, 1889, the French slept fitfully, uncertain what lay ahead for their country. A sense of national and cultural decline had lingered since their defeat in the Franco-Prussian Warof 1870, which ended with the capture of Napoleon III and the loss of significant territory. The people wondered: Did their country’s future lie in the direction of glory, ambition and celebration, or humiliation, degradation and doom?

The tower was intended as a symbol of promise. Eiffel’s behemoth — then the tallest man-made structure in the world — was erected as the centerpiece of the sprawling 1889 Paris Universal Exposition, which was the largest world’s fair to that date. Together, they were to announce that French engineering and technology were unrivaled and that the glory of the nation was to wave forever in the flags flapping from every lamppost and storefront. As Gustave Eiffel declared at the tower’s completion: “France still holds an important place in the world, and . . . we are always able to succeed where others have failed.”

And as Joseph Harriss has recounted in “The Tallest Tower: Eiffel and the Belle Époque,” the exposition’s historian went further in stressing the tower’s importance to France. “This colossal work,” Alfred Picard said, “was to constitute a brilliant manifestation of the industrial strength of our country.”

But to others, the tower was a monstrosity. What was this “odious column of bolted metal,” as some described it, but further proof that the French were ceding their cultural superiority? Artists disgusted by the design issued a letter of protest, asserting: “We have the right to proclaim publicly that Paris is without rival in the world. Along its streets and wide boulevards, beside its admirable riverbanks, amid its magnificent promenades, stand the most noble monuments to which human genius has ever given birth.” And now along comes this “black and gigantic factory chimney,” the letter said, prompting indignation “in the name of betrayed French taste.”

The complaint was so emphatic because anxiety over the state of the nation ran so deep. Most worrying, the government of the Third Republic constantly teetered on the edge of collapse. In January 1889, as the tower neared completion, Georges Boulanger, a popular general on horseback reminiscent of Napoleon, was poised to launch a coup. President Sadi Carnot sat with his cabinet ministers at the Élysée Palace in a state of gloom, knowing there was little they could do to stop Boulanger from taking power. But the death of the Third Republic was averted at the last moment when Boulanger, in a classic French shoulder shrug, instead took his mistress, the Vicomtesse de Bonnemains, to the apartment they shared in the Faubourg Saint Honoré and went to bed.

Another near-crisis came just four months later: Carnot, riding in an open carriage on his way to commemorate the opening of the exposition, narrowly escaped an assassin’s bullet.

This dark side of the Belle Époque also expressed itself in a lust for the macabre: The Paris morgue was one of the city’s most popular sites. Every day Parisians lined up to stroll through the exhibit room, where unidentified children pulled from the Seine or unknown women murdered in back alleys were laid out for viewing — sometimes with touching scenic effects — in the hope that visitors could help identify the dead. “All day long a multitude of the curious, of the most diverse ages, elbow and jostle one another from eight in the morning until nightfall in the public gallery,” a contemporary medical inspector wrote. Commentators described the morgue as theater for the masses. “It is nothing but a spectacle à sensation, permanent and free, where the playbill changes every day,” a journalist explained.

Similarly, drunken spectators often surged toward the guillotine at public executions. “Suffice it to say that the city and its inhabitants strike me as uncanny,” Sigmund Freud wrote home when he was a medical student in Paris in 1885. “The people seem to me of a different species from ourselves; I feel they are all possessed of a thousand demons.”

In such a setting it was little wonder that the Eiffel Tower became a magnet for the disheartened seeking a path to death. In one gloomy case, a troubled workman climbed about 50 feet up the structure two years after it opened, stripped and hanged himself, leaving behind a note instructing that his discarded clothing should go to Gustave Eiffel.

From its earliest days, however, the tower also was part of the festivities of Paris. The act of climbing its stairs or riding in its original elevators turned the structure into an amusement in an entertainment-crazy city. Visitors could dine and drink in the restaurants and bars, and some dropped little balloons off the edge with their names and addresses inside, asking recipients to find them for a visit, a game that added a sense of mystery to the idea of play.

By its sheer height, the tower forced Parisians to look at the world differently — and even to ponder what lay on the horizon. Visiting its peak gave one a palpable sensation of the new vistas opened by science and technology. As one person riding to the top put it: “At a height of 350 feet, the earth is still a human spectacle; an ordinary scale of comparisons is still adequate to make sense of it. But at 1000 feet, I felt completely beyond the normal conditions of experience.”

Though initially rejected by the artistic community, the tower soon delighted visual artists — painters, photographers and, later, cinematographers. Early among them was Georges Seurat, who in 1889 rendered the brand-new structure in an image of misty pointillism. The painter Henri Rousseau placed the tower in a portrait-landscape in 1890, and later it became “as familiar in his paintings as the street lamp,” according to Shattuck. Rousseau used the tower both as a symbol of his environment and for compositional purposes. “For centuries,” Shattuck writes, “the cross fulfilled the same basic functions in religious paintings.”

Besides reflecting the unsettled world from which it sprung, what, really, was the point of this largely useless structure? Among the many seeking an answer, perhaps the French philosopher Roland Barthes has come closest. He first reduces the tower to its essence, asserting that it is really nothing — it’s not a museum, there’s nothing to be seen in it, it’s an empty monument. Why, then, do people flock to it? Barthes offers a simple reflection: It stirs the human imagination. When we apply our own vision to it — each one of us separately — the tower then becomes “the symbol of Paris, of modernity, of communication, of science or of the nineteenth century.” It even potentially becomes, in Barthes’s view, a “rocket, stem, derrick, phallus, lightning rod or insect.”

“In the great domain of dreams,” he concludes, “it means everything.”

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Steven Levingston is the nonfiction editor of The Washington Post. He is author of “Little Demon in the City of Light: A True Story of Murder and Mesmerism in Belle Époque Paris” (Doubleday, 2014) and “The Kennedy Baby: The Loss that Transformed JFK” (Washington Post eBook, 2013).