Most of the time a big day in the BBC Newsroom is defined by the stories. The Japanese tsunami. The death of Gaddafi. The Eurozone crisis. The Diamond Jubilee.
Today is a different kind of big day for BBC News. Our new Newsroom in central London is open for business.
At 11:00 BST we broadcast World Briefing live from studio SL1 for World Service audiences and our World online team has been publishing coverage of the US heatwave, the floods in Russia and events in Syria from the new Newsroom for our UK and international online news services.
Many other teams are already working in other parts of New Broadcasting House - including all the BBC's international language services. But today is the day when the BBC Newsroom at BH gets up and running.
NBH is a wonderful new home, constructed to the east of the original BBC Broadcasting House with its beautiful prow fronted by Eric Gill's famous sculpture of Ariel. Now seven floors of striking glass and steel complement the original Portland stone, curving around a new welcoming piazza just north of Oxford Circus. In terms of funding, the new development has been financed by a public-private partnership involving a special bond, and the overall move has enabled savings for the BBC of an estimated £736m. More details here.
Over the next few months the journalists now working in the Newsroom will be joined by many others. Next, UK Online, World News and the team that produces the summaries and bulletins on Radios 2, 3, 4 and 6 Music will be moving in.
They'll then be joined by the News at One, Six and Ten, the BBC News channel and our newsgathering staff. Our video editing and graphics teams, studio directors and studio managers are also moving in, developing and testing all the new kit right through until early next year when the newsroom will be fully operational.
Until then, we'll still be making much of our news output at Television Centre in west London. But today is an important milestone, as the BBC's future Newsroom starts work.
New Broadcasting House gives us new studios, new operating systems and new technology. But more than this, it offers our journalists a purpose-built newsroom fit for the 21st Century, truly transforming the way we work.
We are bringing all our journalists who serve UK and global audiences together for the first time. Our coverage of international news for audiences in the UK will be strengthened by working alongside colleagues from World Service.
And we have the chance to make sure that the right teams are working together to support sharing of ideas and content. We know that audiences get their BBC news from various platforms - radio, television and digital - from connected televisions to PCs, mobiles and tablets, and in the new Newsroom it will be easy to share what we do across those devices.
Our job is to do the very best high quality journalism we can, and then make sure it reaches you however you choose to get your news. New TV studios also give us the opportunity to refresh the look and feel of our news programmes, and we'll be using the backdrop of the building itself to give audiences a sense of the quality and openness of the building.
In the high-ceilinged space filled with light from the building's windows and atria, our international web team and World Service radio news team are now in place. Our job in New Broadcasting House for years to come is to produce brilliant BBC news services from an ambitious newsroom. That work starts today.
Mary Hockaday is head of the BBC newsroom.