Inside London's most expensive rental: $99,000 a week

If you think your rent is high, consider the poor billionaires renting at the Knightsbridge in London.

According to Cameron Pearson, a luxury real-estate firm specializing in high-end London properties, the penthouse at the Knightsbridge is now renting for £60,000 a week for short-term rentals, which works out to close to $99,000 a week, or just under $400,000 per month. You can get a discount—renting for only $41,000 a week—if you rent for more than six months.

By way of comparison, New York's most expensive rentals are about half that price. Jonathan Miller, of appraisal firm Miller Samuel Inc., said he knows of at least one rental in New York, at the Waldorf Towers, that lists for $200,000 per month. But that's among the highest in town.

So, what do you get for $14,000 a day—or $590 per hour—at the Knightsbridge?

Cameron Pearson said the penthouse, overlooking Hyde Park, is about 8,600 square feet, with six bedrooms and seven baths, including his-and-her bathroom suites with their own terraces. It also comes with parking and a porter.

A spokesman for Cameron Pearson said interest has been strong, mostly from rich overseas businessmen staying in London.

"It's the only penthouse of its kind for rent," he said.

Have a look for yourself.

The dining room has seating for at least 14 people. When guests are not looking at the views over Knightsbridge and Hyde Park through the floor-to-ceiling windows, they may be admiring details like the Swarovski crystal detailing in mirrored bar and wall units in the room.
Source: Wellington Court Property
The penthouse features five reception and entertaining rooms. This one has a baby grand piano.
Source: Wellington Court Property
The master bedroom, with its all-white interior, was created to be a soothing retreat. The carpet is silk and the leather headboard has Swarovski crystal detail.
Source: Wellington Court property
The master bedroom has his-and-hers bathroom suites. The "her" bathroom, pictured here, is lined with Calacatta marble to complement the all-white interior of the bedroom.
Source: Wellington Court Property

—By CNBC's Robert Frank