HSBC's investment in Birmingham will send ripples across Europe, according to city leaders.
Marketing Birmingham chief Neil Rami said the banking giant would become an "anchor tenant for Birmingham" - showing it was a city open to big brands and front-office operations.
Birmingham City Council leader Sir Albert Bore said it was a statement about aspiration in the city.
"We have got faith in ourselves. I think that is important," he said.
"We know we can make this a city of economic growth – it already is – six per cent increase in GVA last year, the highest of the core cities and twice the increase of London.
"We know we can make it work here but we also know there are major issues still to overcome. We know we have areas of the city where unemployment is in double figures. That is why we have launched the East Birmingham Prospectus.
"If we are to ensure this economic growth works for the people of Birmingham then we have got to make sure it benefits the people in those deprived areas."
Mr Rami, chief executive of inward investment body Marketing Birmingham, said there were three reasons why it was "perhaps the most significant investment for Birmingham".
He identified as key aspects the fact it was a headquarters, so decision-makers would be based in the city, its potential boost to the property cycle by being at Arena Central, overlooking a key regeneration site and the long-term commitment to the city.
He added: "If you look at inward investment across the world very often it requires a marquee brand to instill that level of confidence into a city and into a market.
"To be honest, something like this will not only be an anchor tenant for Arena Central - it is potentially an anchor tenant for Birmingham."
Mr Rami said Marketing Birmingham started talking to HSBC in 2012 and about the ring-fenced bank for the past six months.
Phil Miller, chief executive of Miller, which is developing Arena Central, said: "This will enable us to push ahead with realising the full scale of the scheme and deliver HSBC's requirements and our vision for this key site in the heart of the enterprise zone."