Bristol's year as European Green Capital has been officially launched with a high-wire stunt 30m (100ft) above the city.
Bristol is the first city in the UK to be given the status and has taken over the title from Copenhagen in Denmark.
Jade Kindar-Martin from Cirque Bijou cycled on the tightrope with trapeze artist Karine Mauffrey hanging below.
Tony Juniper, Bristol 2015 ambassador, said the city had a "leading role" in showing the world how to be green.
The stunt took place between two warehouses close to the Cumberland Basin.
"I am looking forward to Bristol providing the kind of inspiration needed to shape a different future than the one we are presently heading toward," Mr Juniper added.
The high-wire act, named Bridging the Gap, was designed to symbolise the difference between good green intentions and actually carrying them out.
Environmentalist Jonathon Porritt said: "Both in the UK and internationally, we're way off the pace in terms of improving the state of the environment.
"Bristol has a unique opportunity to show exactly what now needs to be done - in practice, not in yet more buckets of 'greenwash'."
The initiative rewards cities making efforts to improve the urban environment and create healthier and more sustainable living areas.
Events through the year include the launch of what it is claimed will be the world's first solar-powered balloon and a "greentech" camp for children and teenagers to learn about green technology.
Previous title holders are: Stockholm in 2010, Hamburg in 2011, Vitoria-Gasteiz in 2012, Nantes in 2013 and Copenhagen in 2014.
Ljubljana, in Slovenia, will take over from Bristol in 2016.