Hundreds of runners wearing specially-designed luminous suits are marking the start of the Edinburgh International Festival.
Arthur's Seat, one of the city's most famous landmarks, is being illuminated throughout the three-week programme, as runners make their way to the summit as part of NVA's Speed of Light show.
The event, also part of the London 2012 Festival, will see Edinburgh's extinct volcano in Holyrood Park light up in a mass choreographed act of walking and running.
Members of the audience become part of the work by carrying walking staffs which light up and give out individual sounds, triggered by movement and altitude.
Festival director Jonathan Mills said: "It's a mass participation project, it brings sport and art and technology together in a great community celebration.
"We have used the Olympics as a convenient context in which this works best of all. When the eyes of the world are on the UK and when we are thinking about sport, and especially when politicians are talking about the participation in sport, this is a perfect example of bringing together various worlds and colliding various worlds of art, sport and technology.
"I hope what we see and what we hear on Arthur's Seat will inspire others to think about their environment in their city and the way in which their local community and sporting groups and organisations can contribute to their own festivals."
Throughout the festival, which runs from August 9 to September 2 at various venues across the city, almost 3,000 artists from 47 nations will put on performances of dance, opera, music and theatre.
The sell-out opening concert at the Usher Hall tomorrow night will honour the 150th anniversary of Frederick Delius, one of the core inspirations of this year's programme.
Shows include two adaptations of Shakespeare plays, a new production of Gulliver's Travels and a performance from violinist Nicola Benedetti, who is to play at the festival for the first time.
On Saturday, the festival's new theatre venue, the Lowland Hall at the Royal Highland Centre at Ingliston, opens with a Polish adaptation of Macbeth set in the Middle East.
In the days following the Olympics, the first International Culture Summit will be hosted at the Scottish Parliament, in partnership with the Scottish Government, UK Government and British Council.
It will provide a platform for culture ministers from around the world to hold discussions on the role of culture in international dialogue, organisers said.
On the final night, more than 100,000 fireworks will be set off, choreographed to music, in the annual display.
The festival follows the official launch of Edinburgh Festival Fringe which got under way last Friday.