By Maggie Shiels Claude the albino alligator relaxes in a swamp complete with a heated rock while all around him workmen battle against the clock to put the finishing touches to the largest public green building in the world. The California Academy of Sciences, based in San Francisco's Golden Gate Park, opens its doors to the public this weekend following three years of construction and 10 years of planning. The 410,000 square foot (38,000 square metre) structure is just as big a draw as the exhibits it houses. Designed by Renzo Piano, a winner of the most respected prize in architecture, the Pritzker, the Academy has green credentials running through every sinew and vein: from the planetarium to the aquarium and from the rainforest to the living roof which mirrors the hills the city is built on. "People from all around the world are looking at this building," explained Chris Andrews, the chief of public programmes at the Academy and also the director of the Steinhart Aquarium. California academy of sciences As the finishing touches are applied, T-Rex doesn't let the frenzy bother it The list of sustainable design features is seemingly endless: non-toxic insulation, a passive heating and cooling system, a recycled steel structure and electricity provided by some 60,000 photovoltaic cells. Over the next couple of months the US Green Building Council is expected to confirm its highest award on the building, a platinum Leadership in Energy and Environmental Design rating. 'Science is cool' But there is more to the Academy than its greenness, and those that run it have said they have a clear mission to "explore, explain and protect the natural world." "One thing we desperately want to do at the Academy is start to impress upon people that science is cool, science is fun," said Dr Andrews as he wandered through the world's deepest living coral reef display complete with more than 4,000 reef fishes. "We want to emphasise to people that we are fascinated by the natural world and that we are passionate about it." To drive home the fun and interactive aspects of the museum, Dr Andrews demonstrated a game with a Wii-type device that visitors wave in the air to catch bugs and butterflies. dr chris andrews Science and nature doesn't have to be boring said Dr Andrews Another display employing overhead cameras and sensors lets visitors sweep their hands and feet over the ground to move food around for insects while another lets them play scientist and inspect some of the wonders stored in the Academy's vast research facility. "We want people to touch the stuff and as far as possible we want it to be the real stuff," an enthusiastic Dr Andrews told BBC News. 'Major change' The crowning glory of this new $488m (