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Steel, concrete(混凝土) and glass are the usual materials in any skyscraper. But more high buildings are now using wood.
In the last four years, Australia, Norway, England and Canada have all built wooden skyscrapers. The latest one is in Sweden, a new, 19-storey wooden hotel called "Sida vid Sida" (Side by Side).
Why are wooden skyscrapers being chosen ahead of concrete ones? Let's find out.
Is it strong enough?
Wood has been used in many Chinese buildings for thousands of years, but is it strong enough for skyscrapers?
"There's a lot of new materials made out of wood that are able to build big buildings," material expert Dr Michael Ramage told CNN when he was interviewed.
Architects (建筑师)have done thousands of experiment to make sure it is. They place layers of wood across one another coated with special glue to create very strong material.
Wood also lasts a long time and doesn't break down if it is well looked after. The examples include the rooftops of Beijing's Forbidden City and some 700-year-old houses in England.
Ramage also said on the internet that bamboo could be cut in special ways to make it even stronger than normal wood.
Won't it catch fire?
Wooden buildings sound dangerous when it comes to fire. But experts say they may be safer than concrete ones if there is a fire.
"Wood doesn't burn in the way the public imagines," Ramage said. Very small pieces of wood catch fire easily, but very big pieces of wood are quite hard to set on fire, he said.
