It's been five years since New Yorkers were first introduced to the concept of The Lowline, which aims to be the world's first underground park and a natural inverse to the High Line, as it will be similarly built on unused tracks—this time under Delancey Street on the Lower East Side. Taking the idea from aesthetically-pleasing rendering to reality is far from a simple process, involving lots of money and bureaucratic red tape, but the project just took a giant step forward: the city announced its first official approval for the subterranean park this morning, and the project is now greenlit to proceed in the trolley terminal space.

The Williamsburg Bridge Trolley Terminal, adjacent to the Essex Street subway station, hasn't been used since 1948, but before then, it was a station and turning loop for streetcars headed to Brooklyn across the Williamsburg Bridge. The property is owned by the city, but has long been leased by the MTA, a fact that's appeared one of the biggest obstacles to the park's realization. However, in 2013 the MTA indicated it might be interested in transferring the lease, and last fall, the New York City Economic Development Corporation and the MTA put out a joint request for proposals for the trolley terminal's use.

Today, the city announced that the Lowline's proposal has been selected, and that it can move forward once its creators meet a number of conditions, such as raising $10 million and presenting schematic design documents within the next year. They'll also have to host regular public meetings on the park to solicit community input.

It's worth noting that the MTA still technically has the lease on the space, as an EDC spokesperson confirmed today. However, it's expected that the MTA will surrender the lease before the Lowline takes control of the space. The MTA didn't respond to a request for comment.

Community Board 3 gave the project its approval back in 2012, but as recently as December, the board was backtracking, citing concerns that it hadn't been adequately kept in the loop on the planning process and that the Lowline might increase rents in the neighborhood, as happened in Chelsea after the construction of the High Line. Today, however, CB3 Chairperson Jamie Rogers welcomed this step forward, calling it an "important milestone for furthering community engagement with the Lower East Side's residents and businesses who want to ensure that what is created truly benefits those who live and work here."

But concerns of increased property values in the area still resonate with locals, especially given that the park will be directly underneath the $1.1 billion, 2 million square foot Essex Crossing development, which is bringing 1,000 new residential units to the area, along with a fitness center, bowling alley, and urban farm.

Deputy Mayor for Housing and Economic Development Alicia Glen, who's been a major proponent of the project so far, argued that those concerns aren't necessarily relevant: she told NY Mag that "anyone who thinks this is about gentrification, it's not...What's happening above ground is happening. This is about bringing an acre of open space to a neighborhood starving for it, and they're starving for it because there's nowhere to build it anymore. Except now we've found somewhere."

The space itself is envisioned as part-park, part-event space, capable of hosting art shows, performances, and events. It'll use innovative technology involving fiberoptic cables to transmit sunlight from the roof to the subterranean space, allowing plants to grow underground.

"I never even thought we’d get this far," co-creator Daniel Barasch told NY Mag. "It's basically like a giant version of, when you were a kid, using a magnifying glass to focus light to burn leaves and melt toy soldiers."

The Lowline still isn't a done deal: it'll have to go through the city's exhaustive Uniform Land Use Review Procedure, and then there's the small matter of actually funding it. The park's expected to cost about $60 million to build, and $4 million annually to maintain. Despite giving the project the go-ahead, the city hasn't committed to funding it, though Glen told NY Mag that public funds haven't explicitly been ruled out. Barasch told us this fall that the funding will probably come from a mixture of sources, including public funds, private sponsorship, corporations, and foundations.

If all goes well, Barasch and his cofounder James Ramsey are hoping to have the park up and running by 2021. In the meantime, you can get a taste of what it might be like at the Lowline Lab, an environment mimicking the future subterranean park but located at 140 Essex Street, above ground. The Lab was prominently featured in a recently-released promotional video for James Murphy's musical subway turnstiles, which, after being rejected by the MTA, are now being marketed in conjunction with the park.

Get a glimpse of the glitzy future: