On top of the world - Monaco's world record HK$3.3b penthouse

From atop the Odeon Tower penthouse, residents will be able to launch themselves down a slide, plunging two storeys into the open-air infinity pool below.

It's just another day in sun-kissed Monaco, the playground of the super-rich. In the harbour, gigantic yachts jostle for position while, outside the casino, souped-up sports cars speed past. But there is a new arrival to this hottest of wealth hotspots. The Odeon Tower is the beacon of "super prime" property, one of Europe's tallest residential towers topped with what is marketed as the world's most expensive penthouse.

For those who already have it all, the Odeon Tower has a little more. When completed next year, the penthouse will have its own gym, sauna, cinema, library, whisky bar and billiard room, plus a master bedroom the size of two-and-a-half tennis courts - spread over five double-height floors. There will be tables upholstered with the skin of stingrays and shelves crafted from ebony. Rooftop hot tubs will bubble next to walls trickling with waterfalls.

After dinner in one of the six salons (prepared in one of the four kitchens), guests will ascend a marble staircase to a nightclub with a marble dance floor. From there, they will be able to launch themselves down a curving slide, plunging two storeys into the open-air infinity pool. And the price tag? Around £260 million (HK$3.3 billion) - more than three times the HK$819 million cost of a four-bedroom property at Hong Kong's Twelve Peaks.

"This is for the serious oligarchs, the wealthiest of the wealthiest," said Edward de Mallet Morgan, of estate agent Knight Frank, whose task is to find a buyer.

The principality has long been a haven for those with assets to hide, but the Odeon Tower is a new phenomenon, the result of increasing pressure on the 2 sq km microstate. For 30 years, there had been a tacit ban on building tall, following the boom of luxury apartment blocks in the 1970s. The prohibition led to a plan to extend into the sea: a Dubai-style peninsula that would provide an extra 15 hectares, but Prince Albert blocked the plan in 2008 when the financial crisis hit. The only option was to go tall.