The tiny principality of Monaco, nestled on the French Riviera, is best known as a playground of the rich and famous. But it could soon garner a reputation for more than its glamourous Grand Prix and numerous casinos. It's now home to what could become the world's most expensive apartment: the 3,300-square-meter, quintuplex "Sky Penthouse" in the soon-to-be-completed Odeon Tower. Developed by Groupe Marzocco – a luxury real estate company – the double skyscraper of 70 apartments will tower over the principality at 170 meters high.

It promises future residents the "five-star experience" with a 24/7 concierge, an entertainment area (with private movie room and lounge ) and a "wellness centre", including a gym, sauna, private spas and a selection of pools. Spread over five floors, the penthouse property will include, among other things, a kitchen on each floor, five bedrooms, a living-room, dining-room, private home-cinema, sauna and a swimming pool – which is also accessible via a slide. Scheduled to be completed in September 2015, the Marzocco family is expected to put it on the market for around $400 million, potentially making it the world's most expensive apartment.