Alain Robert, dubbed the French spider-man, has scaled dozens of tall structures without ropes or harnesses, including the Eiffel Tower in Paris, the Empire State Building in New York and Malaysia's Petronas Towers in Kuala Lumpur.

It took Robert about 40 minutes on Tuesday to scramble up the downtown Cheung Kong Center -- the flagship building of Hong Kong's richest man, Li Ka-shing. Upon reaching the top of the 270 meter building, Robert waved to a crowd of spectators on the ground below.

The 46-year-old said police officers questioned him after the ascent, but released him without any charges.

Robert said he hoped his climbs could help bring attention to the world's environmental problems.

"The global warming is something that is going to affect the next generation," Robert told reporters on the ground level. "The future is really compromised if we are not doing anything."