Like the building itself, the cats which roam freely around the basement of the Hermitage in St. Petersburg have endured through changing fortunes.

Originally brought into the massive Baroque building by Empress Elizabeth I to catch mice, the 65 felines have outlived and even replaced the Tsars which adopted them.

Treated like royalty down in the "Cat's Quarters," they enjoy 24-hour veterinary care, feeding, and freedom from the adoring public thanks to their own press secretary.

Catherine the Great reportedly called them the "Guardians of the Galleries." Though they aren't allowed into the galleries of what was once the Winter Palace and what has become the largest museum in the world, and most people don't know they exist.

However it's not rare for a visitor outside the building to come across a feline lounging in the sun.

After the Soviet Union collapsed in 1991, many in St. Petersburg could no longer afford to feed and care for their cats, and so the Hermitage, which had been open to the public for more than 100 years, decided to adopt some of the strays to add to the descendants of the original cats brought from the city of Kazan 100 years before that.

Now as then, the Hermitage will take in stray cats that find their way into the museum's underbelly, perhaps by befriending one of the furry staff members. These are given a new life and kept fed and healthy, mostly through staff and visitor contributions.

"If mice would pass close to our cats—they will catch," Maria Haltunen, the official spokeswoman for the cats, told CNN. "They do their job very well." Haltunen told ABC News that most of the time the cats need not kill anything, as their smell serves to keep most mice away.

Many of the cats' ancestors have been immortalized for their service to the state in paintings on the very walls of the museum they defended.

It's all part of the rich tapestry of history the building, with its art, architecture, history, and its feline guardians, has woven through some of the most devastating and destabilizing events in human history.

(WATCH the CBC video for this story below…)

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