A five-minute primer on an issue making headlines Work has finally started on New York's Freedom Tower, the skyscraper that will rise from the site of the World Trade Centre. It has been almost five years since the 9/11 terrorist attacks. How long will the work take? The Freedom Tower is scheduled to be finished by 2012 but it has been a fraught process getting to this stage, with repeated disputes over redeveloping Ground Zero. Until last month the site's landlord, developer Larry Silverstein, and its owner, the city's Port Authority, were at loggerheads. But a deal has been done and Mr Silverstein will build four of the five skyscrapers on the site. On completion, he will hand over the Freedom Tower and another building to the authority. The Freedom Tower's design has changed several times. What does this blueprint look like? It will be among the world's tallest buildings at 82 storeys - the same number as the Twin Towers destroyed in 2001. With its decorative spire it will reach 540 metres, or 1,776 feet, a figure that matches the year of American independence. It was initially envisaged that the building would encompass a swirling design evocative of the Statue of Liberty, but police said it would be vulnerable to truck bombs similar to one used to attack the Twin Towers in 1993. The new building will have a 60-metre blast-resistant base coated in titanium to withstand any repeats. How much support is there for replicating the height of the Twin Towers? Opinion is divided. Some victims' families feel the scale of the new tower will make it another terrorist target. Others, such as New York Governor George Pataki, say the American people should not be forced to build low in the face of the 'war on terror'. Tell me about other developments planned. The tower is just part of construction and infrastructure projects totalling US$9.9 billion. There will be a 9/11 memorial and museum, a retail block, three commercial buildings and a block of flats on the site of the Deutsche Bank building, which was badly damaged in the attacks. The entire project will create 820,000 square metres of office space, but how will companies be enticed to move to the Freedom Tower? No one's sure, and many people, for obvious reasons, would be unwilling to work in the building. No firms have committed to space in the tower but the Port Authority has guaranteed about half of the space will be occupied by government agencies.