The water-bound fort on an abandoned artificial island in the Gulf of Finland holds an eerie past.

       Fort Alexander I, also known as the "Plague Fort" near St Petersburg in Russia was built in 1845 as a military base but soon repurposed for disease research, including studies on cholera and the bubonic plague.

       The fort was built to protect the Baltic waterway to Saint Petersburg and played a defensive role during the Crimean War, deterring attacks with its fortifications and early naval mines.

       The "Plague Fort" of over 5,000 square meters was capable of holding up to 1,000 soldiers, with 103 cannon ports and room for 34 additional guns on the roof.

       By the late 19th century, advancements in artillery rendered it obsolete, and it was eventually removed from the Russian military register in 1896.

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       Its isolated location made it ideal for testing viruses, though some researchers themselves contracted the diseases.

       In the 1890s, following the discovery of the plague pathogen, the Russian government established a research laboratory at Fort Alexander to study plague and develop vaccines.

       Renovated with funding from Duke Alexander Petrovich of Oldenburg, the facility focused on bacteriology and serum development, although dangerous work led to several cases of plague among staff before the laboratory ceased operations following the 1917 Russian Revolution.

       After 1917, the fort was owned by the Russian Navy, used for storage and repairs until it became abandoned in 1983.

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       The fort later became a hotspot for illegal raves and is now a popular site for tourists.

       Since 2005, it has been managed by the Constantine Palace administration which stopped the rave parties.

       From 2011, the site can now be visited by boat to see the island and the legendary fort near St. Petersburg and Kronstadt.