A six week filming schedule for the new Avengers: Infinity War movie is estimated to generate more than £10m for Edinburgh.
It is the largest and most complex shoot ever to film in historic Old Town and other locations in the capital's city centre.
More than 400 crew have been working on the project, which started in the city on Wednesday.
The production's first schedule with cast in the city will be in mid-April.
Avengers: Infinity War stars Robert Downey Jr, Chris Evans, Chris Hemsworth, Scarlett Johansson, Mark Ruffalo, Anthony Mackie, Jeremy Renner, Elizabeth Olson and Paul Bettany.
The film is directed by Joe and Anthony Russo.
Mr Russo said: "When Edinburgh came up as a location option we jumped at the chance.
"The city is such a unique and iconic location, but one never seen as the backdrop for a big action film, which is incredibly exciting.
"We appreciate the entire city's help and are excited to have such a beautiful and historic city in the film."
Gavin Barrie, City of Edinburgh Council's economy convener, said: "Our cobbled streets, historic properties and stunning green spaces could set the scene for some of cinema's greatest superheroes and it is fantastic to secure such an A-list production.
"We know 40% of visitors to the UK are attracted to places they have seen on screen and the Marvel franchise offers a huge opportunity to promote Edinburgh all over the world.
"This is fantastic news for the city and our film industry.
"The council will do all it can to support Film Edinburgh and the producers and keep the city moving throughout the shoot."
Rosie Ellison, Film Edinburgh film manager, said: "This is the biggest production to ever film in the region.
"But crucially, it also clearly demonstrates Edinburgh has the infrastructure and process in place to accommodate major filming of this scale.
"The reinforcement of the Edinburgh Film Charter, which was ratified again a few years ago, has played a massive role in simplifying procedures and allowing the city to gear up and facilitate productions of all sizes.
"Film Edinburgh and the council have worked closely with the filmmakers for over a year to coordinate the smooth running of the location shoot in the region."