LITTLE ROCK, Arkansas (AP) -- Visitors to Bill Clinton's presidential library probably wouldn't guess that they're treading on rubber-tire floors and looking up at soda-can ceilings. But the library now offers a special "green" tour to feature its environmentally friendly construction.Before architects started designing, they knew former President Clinton wanted his library on the banks of the Arkansas River to be energy efficient. The final product was the first and only presidential library to earn an award from the U.S. Green Building Council for environmental design.The library started offering the "green" tours in late September for a weekend meeting of the American Solar Energy Society. But the tour proved so popular that the museum now offers it each Saturday and for groups upon request.David Williams, a library volunteer, gives the tours. He points out that even the library's location is relevant to the theme."This land was a contaminated brownfield," he said. "We've gone from a contaminated piece of property (to one) that now is a city park."The center received a "silver certification" in Leadership Energy & Environmental Design, a rating system administered by the U.S. Green Building Council, which promotes environmentally responsible and high-performance buildings. There are four LEED certification levels for green buildings -- platinum, gold, silver and certified, with platinum the highest.On the second floor of the library, Williams points out the 143,000 pounds of glass windows that allow natural light to flow into the building.Clinton, Williams said, "wanted maximum light, natural light, in here."But too much light could also damage the library displays, so 258 double-layer panels were placed on the side of the building, outside the glass, to filter the light.Williams points to the black floor. "You're standing on rubber, recycled. Most of it is tires," he said. The wooden floors are made of bamboo, a rapidly renewable product.Downstairs, Williams says, "these ceilings are recycled aluminum. About 75 percent (of) aluminum, is recycled soda cans."And outside there are 336 solar panels on the roof, one of the building's energy sources.The parking lot features bicycle racks and three stations where electric cars can recharge. There are also newly planted trees, and in five years, when they're fully grown, they will provide shade for 50 percent of the parking places.Copyright 2005 The Associated Press. All rights reserved.This material may not be published, broadcast, rewritten, or redistributed.