You can find London's smallest police station tucked away in the southeast corner of Trafalgar Square.

But you can also be forgiven for missing it: it looks more like a neoclassical Tardis than a police station, and there won't be a crowd of tourists gathered around it, merrily snapping away on their cameras.

Though the Lilliputian cop shop is not among London's most popular visitor attractions, it's certainly unique. It was built in the 1930s to serve as a watch-post, an eye on Trafalgar Square, which is a magnet for London's protesters, rioters, marchers, and pigeons.

Inside, there is only room for a single person. Sadly, if you peer through the windows these days, you won't see a bored bobby, just lots and lots of mops. The station is now used as a storeroom for cleaners.

In its heyday, the station was fully prepared for even the most passionate protests. It had a direct telephone line to Scotland Yard and castle-style slits in the walls to allow the single officer inside to shoot at rioters, which would of course only have made the riot worse—and probably made the lone officer a target of the rioters.

Next time you're in London, be sure to pass by Trafalgar Square and see this tiny marvel for yourself, mops and all.