The three million works of art at the Hermitage Museum in St. Petersburg, Russia, are protected from rats and mice by a small army of about 65 cats rescued from the streets.

The museum, which is one of the largest in the world, draws millions of visitors every year, but few see the feline rodent killers who are restricted to the basement. The four-legged guards are fed and pampered by three people who work almost full-time tending to the cats.

"They're not just mascots, they're really employees of the Hermitage and they play a very important role," says Irina Popovets, who spends six hours a day caring for the felines.

The tradition of having cats at the Hermitage dates back to 1745, following a decree signed by Empress Elizabeth, daughter of Peter the Great.