Fort Alexander I may have been built to defend St. Petersburg from attack, but it would go on to become synonymous with disease.

It’s 1899, and in a mysterious fort just off the coast of St. Petersburg, Russian scientists are conducting probing experiments on animals that could well kill them. And if the test subjects do ultimately perish, the researchers will have no choice but to burn the bodies on the same site. For you see, the threat posed to humans as a result of these investigations is also very real.

But just why were the scientists in that remote building, and how did they come to be embarking on potentially deadly work there? Well, interestingly, Fort Alexander I was named after the Russian emperor who ruled as Tsar from 1801 until 1825. And, initially, the stronghold was built to protect the imperial Russian capital of St. Petersburg from attacks in the Baltic Sea. At that time, you see, the city was vulnerable to naval assault along the Gulf of Finland – the eastern arm of the Baltic.

What’s more, the Gulf of Finland was a key part of Russian strategy after the founding of St. Petersburg in 1703. The city’s importance only increased in 1713, too, when it took the place of Moscow as Russia’s capital. And apart from a short break in the 18th century, St. Petersburg retained that honor until 1918.

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Back in 1824, though, a devastating flood of the River Neva swept away the city’s largely wooden and earthwork defenses. In fact, the deluge was the biggest in St. Petersburg’s history. Owing to that catastrophe, then, Tsar Nicholas I decided that it was time for new protective structures. And this time around, they would be built to last in stone.

Yet although plans for the fort were drawn up some three years after the flood, construction didn’t actually start until 1838. Alexander wasn’t completed and brought into service until 1845, either. Then, towards the end of the 19th century, locals gave the building a new and sinister name: the Plague Fort.

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We’ll explain why the fortress came to be called this a little later. But first, let’s take a more detailed look at the structure’s history. As we’ve heard, Fort Alexander I’s purpose was to protect St. Petersburg from assault by sea. And the city’s location on the shores of the Gulf of Finland made it particularly vulnerable to such attacks.

The Gulf of Finland lies at the eastern extreme of the Baltic Sea, with Finland on its northern shore; Estonia, meanwhile, lies to the south. And, somewhat inconveniently, St. Petersburg is located at the point where the River Neva runs into the gulf. So to protect the Russian capital from maritime assault, a string of fortress strongholds was built in the 19th century.

In fact, a first generation of forts was built in the 18th century as a way in which to protect St. Petersburg from Sweden. Russia and Sweden had waged war against each other for centuries, with three conflicts in particular taking place during the 1700s. But as we’ve mentioned, these 18th-century defenses were badly damaged by the great flood of 1824.

As well as Fort Alexander, the 19th-century defenses of St. Petersburg included Forts Risbank, Peter I, Kronsholt and Constantin. These structures also provided a defensive curtain for the important naval base of nearby Kronstadt on Kotlin Island. And the extravagantly named Louis Barthelemy Carbonnier d’Arsit de Gragnac drew up the original 1827 plans for Alexander.

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Mind you, de Gragnac was also known by the Russians rather more simply as Lev Lvovich Carbonnier. He had previously been responsible for the blueprints of an earlier Gulf of Finland fortress, Fort Citadel, which was later to be renamed Fort Peter I. Tragically, though, de Gragnac died in 1836 before the construction of Alexander even got started.

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Incidentally, the engineer who took over de Gragnac’s plans was a Russian of French heritage who also had two names: Moris Gugovich Destrem and Jean Antoine Maurice. In any case, he updated de Gragnac’s proposals, with the result being that building works finally got under way in 1838. Russian engineer Mikhail von der Veide took charge of the new fort’s construction. And the project was certainly an ambitious one.

You see, the scheme didn’t just involve building a fort; it also entailed constructing a man-made island to put the fort on. Strikingly, construction workers achieved this feat by driving no fewer than 5,535 piles – each 40 feet long – into the seabed. That’s right: these piles formed the basis for layers of sand, concrete blocks and slabs of granite.

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Now, the fort itself – which measures around 295 feet by 196 feet – was constructed with thick red brick walls encased in granite. And from above, the building has an incomplete oval shape that can be likened to a kidney bean. But don’t let the rather benign comparison fool you, as the fort was armed to the teeth and ready for action should any attack come.

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Two land-based forts, Constantin and Peter I – each situated on one side of Alexander – completed the harbor mouth’s defenses. But let’s get back to Alexander itself. The magnificent stronghold had had a floor space of almost 54,000 square feet, and it could accommodate up to 1,000 troops.

And Alexander’s defensive capability was certainly formidable. The fort’s walls, for example, incorporated 103 embrasures, or port holes, for cannons, while another 34 cannons could be deployed on the fort’s roof. But for all this daunting firepower, the truth is that troops at Alexander never fired off a shot in anger.

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Still, that’s not to say that building Alexander had been a waste of time. Instead, the fort’s power as a potent defensive weapon came from its qualities as a deterrent. When Russia fought against Britain, France and the Ottomans in the Crimean War, for example, Alexander proved its worth. ;

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And Alexander was made all the more daunting as a defense resource through the deployment of innovative new technologies. In 1853 German-Russian engineer Mortitz von Jacobi had invented a mine designed for use at sea. The device would be attached to the sea floor with an anchor, with a cable running from the mine to a power cell on land. And it would be the cell that detonated the charge – a total of 31 pounds of gunpowder.

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As it happens, the Russians were the first to deploy examples of Jacobi’s invention in the sea around Fort Alexander. And another type of mine was also first used by the Russians in the Gulf of Finland. These were chemical contact mines, which had been developed by the Swede Immanuel Nobel. He was the father of Alfred Nobel, who set aside some of his fortune to establish the prizes that bear his name.

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And so it was in 1854, during the Crimean War, that the British Royal Navy decided to probe the Russians. The Brits thus sailed into the Gulf of Finland towards the maritime defenses of Kronstadt and St. Petersburg. The fleet’s commander, Admiral Sir Charles John Napier, decided against an attack, however, upon seeing the forts and minefields in the vicinity.

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Then in 1855 another Royal Navy squadron – this time accompanied by French ships – sailed towards Kronstadt. On this occasion, mind you, the objective was to firstly clear the minefields using small steam-powered ships. But the mission, which was led by Vice-Admiral Sir Richard Saunders Dundas, was not a success. And again Fort Alexander would play a key role.

You see, although Dundas’ boats managed to clear a few mines, this came at the expense of four of his vessels. What’s more, the operation would push the boats to within the range of cannons mounted on the forts, including those at Alexander. And since Dundas subsequently abandoned his attempt to sail on Kronstadt, Alexander again proved its worth as an effective deterrent.

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After those ultimately uneventful incidents of 1854 and 1855, Fort Alexander was only to be put on alert twice more. Firstly, in 1863 there was a perceived danger that conflict might be rekindled between Russia and the British; ultimately, though, this came to nothing. Then there was the Russo-Turkish War from 1877 to 1878, but no attempt was made on Kronstadt during that conflict, either.

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And as the 19th century progressed, new developments in gunnery much diminished the military importance of forts like Alexander. The rifled barrel, which came into artillery use from the mid-19th century, was one such innovation. Previously, cannons had been smooth bored; thanks to rifled barrels, however, shells could be fired at much higher speeds.

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Inevitably, the higher velocities meant that projectiles could penetrate harder targets, including fortress walls like those of Alexander. Sadly, then, the fort was no longer an impregnable defense. And proof of its new-found vulnerability came from an experiment in Sweden. There, Vaxhom Fortress – which was similar in strength to Alexander – was deliberately shelled from rifled artillery by the Swedish Navy. As you may already have guessed, the modern guns quickly shattered the fortress walls.

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So as the 19th century drew to a close, Russia’s military commanders now regarded Fort Alexander as a redundant resource. As a consequence, then, it was put into use as an ammunition storage dump. In 1896 the authorities even formally decommissioned Alexander alongside two other forts. But that was not the end of Alexander’s story – far from it, in fact.

Unlikely as it may seem, it was a medical breakthrough that would provide the next chapter in Fort Alexander’s life. In particular, in 1894 scientist Alexandre Emile Jean Yersin would identify the pathogen that caused the bubonic plague. Yersin, who was born in Switzerland but later took French nationality, lived from 1863 to 1943.

Yet Yersin was in fact only the co-discoverer of the bacterium that caused the much-feared plague. Yes, although the microorganism was ultimately called Yersinia pestis after the Swiss man, Japanese researcher Kitasato Shibasaburō made the same breakthrough. And, interestingly, both scientists achieved the feat in Hong Kong just days apart.

Fortunately for Yersin, he had something of a march on Shibasaburō, as he had found that the same bacterium was present in both infected rodents and humans. Indeed, this link paved the way for the discovery that plague was transmitted from rodents to humans via flea bites.

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Prompted by this revelation, the Russian government set up the Commission on the Prevention of Plague Disease. The commission was also given the task of carrying out further research into the bacteriology of the potentially deadly illness. But as the work involved was highly dangerous – it involved contact with pathogens that cause the plague, after all – scientists needed somewhere isolated with a high level of security to conduct experiments. And where better than Fort Alexander?

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Therefore, in January 1897 the commission decided that Fort Alexander would be the location of its brand-new research facility. Once there, it would operate under the auspices of Russia’s Imperial Institute of Experimental Medicine. So, in the two years that followed, essential work was carried out to transform the fort into a research center.

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For example, the fort was fitted with laboratories – some with containment facilities to minimize the dangers of working with lethal bacteria. Additionally, there would be a stable that could house 16 horses, as these were the animals that would be experimented on. An incineration facility was also included to safely dispose of any horses that ultimately died.

But it didn’t stop there. Fort Alexander was also equipped with a comprehensive science library, with noted Russian philanthropist Duke Alexander Petrovich of Oldenburg kindly footing much of the bill. As well as being exceptionally wealthy, the duke was himself a medical doctor. In 1899, then, everything was ready at the fort, meaning the important research could commence.

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Now, intriguingly, doctors and scientists – some accompanied by their families – lived at the site itself. That was just as well, as the only means of getting to the fort was by a small steamer that was appropriately named Microbe. Yet while access to Alexander was closely controlled, there were facilities for visitors – even conferences.

Regardless, the main focus for the scientists at Alexander was producing serum and vaccines to combat the plague, and they did this by infecting horses in the hope of immunizing them. Thereafter, the horses’ blood could potentially be used as the basis for vaccines. And as the years went by, the laboratory also searched for inoculations against fatal diseases such as tetanus, typhus, cholera and scarlet fever.

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Unfortunately, it seems that bio-security was not all that it might have been at Fort Alexander. Certainly, the dangers of working with these deadly infectious bacteria proved all too real. You see, there were three cases of plague among the staff on the isolated island in 1904 and 1907. And, tragically, those outbreaks would claim the lives of two researchers.

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By terrible coincidence, one of those who died was the director of the center in 1904, Dr. V.I. Turchaninov-Vyzhnikevich. The other man to perish was Dr. Emanuel F. Schreiber, who had fallen ill in 1907. Schreiber had diagnosed himself as suffering from pneumonic plague – a disease that’s nearly always fatal. And so it proved; he was dead within three days of contracting the condition.

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Ultimately, then, both of the dead men’s bodies were burned in the island’s incinerator. And although this move was made to avoid any risk of further infection, it could very well have caused Turchaninov-Vyzhnikevich and Schreiber’s families great pain. A third doctor, L. V. Podlevsky, also contracted the infection but survived thanks to a vaccine developed at the fort. All in all, it’s little wonder that the fortress research lab earned the name of Plague Island.

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Then it was in 1917, during Russia’s cataclysmic communist revolution, that the laboratory’s work was brought to an end. The project at Alexander was now taken over by other labs in Saratov, St. Petersburg and Moscow, with the result being that Fort Alexander was now redesignated as a mere storage facility by the Russian Navy.

In 1983 the navy abandoned Alexander altogether, removing all fixtures and fittings that could be transported. After that, the fort seems to have been left to its own fate, although it reportedly became a popular venue for illegal raves towards the end of the 1990s and into the 2000s. Plans for a $43 million renovation that were mooted in 2007 also seem to have come to nothing.

So, today, this monumental piece of military and medical history lies abandoned and empty. And while some travel websites claim that tour groups do visit the island, specifics are hard to come by. Unless a wealthy entrepreneur eventually invests in the fort, then, it will stand as a reminder of the brave doctors and scientists who worked to fight deadly disease.