When it opened in 2009, New York City’s High Line, an elevated train track that was converted into a park, instantly became one of the most celebrated modern parks in the world. So it should come as little surprise that New Yorkers are looking to tap the concept and the energy of the High Line in other new urban parks. A group of NYC entrepreneurs have come up with a plan to convert another abandoned rail line into a park on Manhattan’s Lower East Side. The difference: The proposed park will be located entirely underground. A group that includes Dan Barasch from PopTech, money manager R. Boykin Curry IV, and architect James Ramsey recently announced plans to convert a dark, dank subway track beneath Delancey Street into an inviting ‘Low Line’ park. The proposal is not without its challenges. To stream natural light into the subterranean chamber, the group proposes to pump natural sunlight into the underground space using fiberoptic cables and mirrors.