Tonight, lasers and searchlights will shoot across London's sky from the top of its newest landmark, the Shard. To celebrate the completion of the outer structure of Europe's tallest building, the London Philharmonic Orchestra will entertain guests including the Prime Minister of Qatar, Hamad Bin Jassim Bin Jabor Al Thani, and The Duke of York with renditions of Copland's Fanfare for the Common Man and the finale of Stravinsky's Firebird Suite.

Yet there is still no sign that anyone has signed up to take any of the 600,000 sq ft of office space in the building, which stands at more than 1,000 ft. The property firm that part-owns the building and is in charge of filling the space said it is in talks with potential occupants but could not announce any deal yesterday. Irvine Sellar, head of Sellar Property, said he was being "extremely selective" when choosing the people he wanted to do business with on the Shard.

The building, close to London Bridge station, will house three floors of restaurants, a 200-bed, five-star hotel, 10 homes and a viewing platform, which will be open to the public. "It will be fully occupied by the end of 2014; the hotel is being fitted out now and will be open in late spring 2013," said Mr Sellar.

He added: "The viewing gallery is nearly complete and will be open in February next year; the restaurants will be open and operating by spring next year. With the office space, we are being very selective. We don't want one single, overbearing occupant, we want a mix of media, finance companies, etc."

Asked when the flats would go on sale and at what price, he replied: "We are holding back on selling or leasing for some time. We want to evaluate the impact of the building before we make those decisions." Some reports suggested it was perhaps prospective buyers – some of whom would spend much of the time above the clouds – who were being selective.

Despite having put up 95 per cent of the building's cost of around £450m, the Qatari Royal family appear relaxed about recouping their cash. Sheikh Abdullah Bin Saoud Al Thani, governor of the Qatar Central Bank and chairman of the board of directors of Shard Funding Limited, said: "It is a long-term investment; there is no way I can say exactly when [the money will be earned back]. This is part of our relationship with London and our confidence in the London markets."

The skyscraper is joint-owned by the state of Qatar and the Sellar Property Group. Renzo Piano, the architect behind the project, said yesterday he hoped the Shard would become a "social" aspect of the capital. "I hope [people] will feel that this building has a little poetic soul," he said. "It reflects the weather in London, whatever it is."