One of the largest art galleries in the world is relying on feline power to keep it rodent-free.br br For more than 200 years, cats have had a full-time job at the Hermitage Museum in Saint Petersburg, Russia.br br Today, a new generation of about 60 felines live in the building, the proud descendents of a long line of Aristo-cats.br br Al Jazeera's Neave Barker went on a prowl with the rat catchers in Saint Petersburg.