Boris Johnson, Mayor of London, and David Higgins, Network Rail’s chief executive, has marked the 50-day countdown to the opening of London’s newest public space. The mayor laid one of the final paving stones on the new King’s Cross Square, which will open to the public on September 26th.

The new space – which at 75,000 square feet square is big enough to accommodate Big Ben laid down lengthways or more than 300 of the Mayor’s New Buses for London – will give passengers and people in the area improved entrances to the London Underground, an area dedicated to public art, a stunning lighting scheme and double the number of trees.

The square, designed by architects Stanton Williams, is the final part of the £550m King’s Cross station redevelopment, which saw a brand new concourse open last year offering rail passengers three-and-a-half times more space than the 1970s concourse that it replaced. Since the new concourse opened, passenger satisfaction at the station has increased by 33%. The demolition of the old concourse and the creation of King’s Cross Square will reveal the station’s original façade for the first time in 150 years.

The Mayor of London, Boris Johnson, said: “The incredible regeneration of King’s Cross continues apace. Network Rail are renovating this historic location with ingenuity and flair and this wonderful new square will be the perfect gateway to almost 70 acres of new public spaces, businesses and homes for Londoners, setting a new standard that we should aspire to for all future station redevelopment.”

David Higgins, Network Rail chief executive, said: “The new square will be a stunning entrance to the King’s Cross area. It is the last piece in the jigsaw which has led to more than £2.2bn of private investment transforming the area into an exciting centre for business, knowledge and the arts of which the capital can be proud. If ever proof were needed that investment in rail provides a catalyst for wider economic growth, this is it.“

David Partridge, chair of the King’s Cross Business Partnership, said: “King’s Cross is undergoing an incredible transformation and this is being driven in part by investment in transport infrastructure, including the stunning Western Concourse and very soon, the new King’s Cross Square. It is testament to the enormity of the transformation that this will actually be the second major square to open in the area in as many years.

“The King’s Cross Business Partnership welcomes the new square, we have already seen at Granary Square how large scale public spaces can provide a meeting point, an area for people to congregate and pause for a moment, as well as a focus for events, cultural and commercial activity. This is good for the public, good for local businesses and good for King’s Cross.”

The redevelopment of the station area has been a catalyst for one of the largest regeneration schemes in Europe, with 67 acres of brown field land being redeveloped to create eight million sq ft of offices, retail and housing. In 2011, Central Saint Martins College of Art and Design moved into renovated railway buildings to the north of the station. Every day 150,000 people – 28 million a year – go through the railway station.

See video of the progress: