The worlds most expensive residential apartments at One Hyde Park have been officially unveiled with the help of a few famous faces. Gary Lineker, actress Holly Valance and Bernie Ecclestone were among the celebrities who attended the launch party for London's most exclusive address. Around 5,000 gold balloons were released from the roof of the development in Knightsbridge, which as its name suggests overlooks Hyde Park. Around 350 guests were shown the apartments which reportedly start a £6.5m for one bedroom and go up to £140m for a penthouse. Prices average £6,000 a square foot, and are reportedly the highest ever paid for residential space. The venture is the brainchild of the Candy brothers, Nick and Christian who are already believed to have sold 65% of the 86 luxury apartments properties. Secrecy has surrounded the actual cost of the apartments and how many have been sold. Only prospective buyers were given exact details of costs. One Hyde Park enjoy sumptuous shared features including a cinema, a 21m swimming pool, saunas, a gym, a golf simulator, a wine cellar and a valet service. Residents can call on valets, a concierge and butler room service from the next-door Mandarin Oriental hotel's two restaurants, overseen by Heston Blumenthal and Daniel Boulud. The development also contains three boutiques which include Rolex and McLaren.