London (CNN)A daredevil climber known as the "French Spiderman" has scaled a London skyscraper with his bare hands. Stunned office workers took pictures as Alain Robert climbed the 230-meter Salesforce Tower in the UK capital's financial district, occasionally waving to crowds as he ascended. He has been arrested around 120 times for similar stunts since he began climbing buildings 20 years ago, his manager said.