New York’s post-industrial renaissance continues, driven by land re-use, rising demand for residential, office and commercial property and a warm embrace of multi-level, multi-functional public spaces. Hudson Yards is the city's largest real estate development since the 22-acre Rockefeller Center was built in the 1930s. Located between 10th and 11th Avenues, the site is bisected by the curve of the High Line and ringed by a clutch of new buildings, including Diller Scofidio + Renfro's and Rockwell Group's 'The Shed' culture centre and tapering north and south towers, detailed to glossy perfection by high-rise experts Kohn Pedersen Fox. The tallest of these is around 1,200 ft high, offering up stark and lofty surroundings for a new public space in the heart of the 'Yards'.

Jay Cross is the man overseeing the site’s transition into a new chunk of city. The final brick won’t be laid until 2024, by which time Hudson Yards will accommodate offices, homes, shops, a school and hotel and 14 acres of gardens, walkways and squares. ‘Our objective is to create a great public space, a new crossroads for the city,’ says Cross, ‘and we wanted a central piece that would anchor all these buildings.’ That honour has gone to Heatherwick Studio, and the renders shown here mark the public debut of New York’s most extraordinary piece of infrastructure, dubbed 'Vessel' – part building, part sculpture, all accessible and designed to put Hudson Yards on the map.

Vessel is an extraordinary proposal. 'Our work couldn't be about height in a city where everything is about height, so we became interested in the human dimension – the most successful public spaces have the chemistry of interaction,' says Heatherwick. Drawing on his longstanding fascination with stairs and Indian stepwells, and New Yorkers' relentless emphasis on fitness and movement, Heatherwick and his team shaped a structure that could loosely be described as a 'climbing frame for adults'. Formed from a mesh of 154 individual flights of stairs, 80 landings and endless ribbons of balustrading and balconies, Vessel represents one mile of stairs and walkways winding up and up in a 16-storey steel puzzle, an MC Escher-esque construction that's willfully ambiguous but intended to be totally engaging.

‘Thomas is so ambidextrous as a designer – it’s hard to find someone who could move so easily between these specialities,’ says Cross. ‘The first vignette that he showed us was pretty dazzling and really, from the perspective of the design intent, what we are building is exactly the same.’ Every element of Vessel has been designed to serve the public space it sits in, from the narrow 50 ft base that flares out to 150 ft on the upper level, preserving as much park space as possible, to the reflective stainless steel panels (coated in a special copper finish) that are angled downwards to create dynamic views from the ground.

Vessel sits among five acres of urban park designed by Nelson Byrd Woltz Landscape Architects, with input from Heatherwick's team. The new outdoor space is intended as a seamless continuation of the planting and ethos of the nearby High Line, as well as connecting with the new Hudson Park & Boulevard green space. Planting has been inspired by New York's distant past as a verdant woodland, with an integral 200 ft water feature and 28,000 plant species in total. Thomas Woltz, Nelson Byrd Woltz's principal, describes the scheme as 'both technologically complex and beautifully natural', a public space 'inspired in part by the grand piazzas of Europe, including Rome’s Piazza del Campidoglio'.

One of the iconic images of New York is Lunch atop a Skyscraper, a vertiginous portrait of steel, modernity and human adventurousness, taken during the building of the Rockefeller Center. In some respects, the Vessel brings the pioneering spirit of the early skyscraper city to life, its 2,500 steps offering ample challenge to those willing to seek out a high-rise view, the mix of raw and treated metal evoking the hidden cores that hold up the modern city.

When Vessel is finally assembled and opened sometime in 2018, it’ll be up to New Yorkers to decide how it’s used (and named, as Heatherwick acknowledges). ‘As far as we’re concerned we want a great public space that people appreciate and adore,’ Cross says, but he admits it’s hard to predict how many visitors will come and what they’ll do. ‘We’re not sure how far people will walk up,’ he says, adding that only when they saw the piece under construction in Italy did they realise how theatrical the space would be. ‘It’s like a theatre in the round – there are a lot of ways to participate and there will be organised and unorganised activities.’