10 Hudson Yards, designed by Kohn Pedersen Fox, is nine stories out of the ground. It will reach 52 stories.

The steel platform that is vital to the $20 billion Hudson Yards mega-project in Manhattan—what will allow three high-rise towers to be built atop of working railroad tracks on the eastern half of the site—is taking shape, after a slow start. For a time it seemed like the project would never happen at all; the development team was chosen in 2008, but groundbreaking didn’t occur until well after the recession, in late 2012.

But on Thursday, large sections of the lattice-like structure were visible jutting over the ground near the corner of 10th Avenue and West 30th Street in Midtown West. Related Companies, a co-developer, invited reporters to the construction site to survey the progress first-hand and up-close.

So far, 75 of the 300 concrete-filled caissons that will support the platform for much of the eastern half of the project, which spans eight blocks and 15 acres, have been drilled deep into the ground, with some squeezed between railroad tracks, said architect Michael Samuelian, the Related vice president who led Thursday’s tour. Oxford Properties Group is the other developer.

“Rarely do you get to build a neighborhood from scratch,” said Samuelian, who also showed off 10 Hudson Yards, an angular 52-story office tower designed by Kohn Pedersen Fox Associates (KPF) that is now nine stories out of the ground. That tower, which is now 80 percent leased to tenants like Coach, will be the first to be completed next year, because it sits on the ground and did not need a special platform for support.

But the platform, which will sweep across 10 acres, does pave the way for those three high-rises, which include 30 Hudson Yards, an 80-story office tower also designed by KPF. About half-leased, to tenants like Time Warner, it will be the city’s fourth tallest building when finished, though its observation deck will be higher than One World Trade’s, according to a slick multi-media presentation that preceded the tour; a cocktail lounge will be nearby.

Also slated to sit atop the platform is 15 Hudson Yards, a 70-story tower from Diller Scofidio + Renfro, a 70-story tower with condos and affordable rentals. It will connect to a “culture shed,” or kunsthalle-type performance space encompassing 18,000 square feet, but that can retract into itself when the full space is not needed.

And, the platform-supported eastern half will feature 35 Hudson Yards, an 84-story tower by David Childs of Skidmore, Owings & Merrill, which will be layered with a mix of condos, hotel rooms, and offices. Unlike most of the other planned high-rises, its facade will be stone.

The site will also have shops, in the form of a seven-level mall similar to what Related built at the Time Warner Center. Parks will be numerous in the project, half of which will be made up of open space, which could counterbalance the skyscrapers. “We want this to feel like the rest of New York,” not Dubai, Samuelian said.

Also on Thursday, Related confirmed plans for 55 Hudson Yards, a site on West 33rd Street that it acquired from Extell Development Company last year. Its 51-story office building will be designed by Eugene Kohn and Kevin Roche and will target law and financial firms, officials said. It sits on land and does not need a platform. Neither does a block-through site at West 33rd and 10th, currently with a drive-through McDonald’s, although Related hasn’t provided many details about that project, which could start in 2017. Meanwhile, the 13-acre western half of the site, which is lined with Long Island Rail Road tracks, will mostly be made up of residential towers, though construction of that platform won’t begin until at least 2017.

Though it may be one of several massive projects in the greater 45-block Hudson Yards neighborhood, Related’s Hudson Yards is the largest private real estate development in American history, officials say.