Besides the High Line in New York City, this report from Wired describes the “Low Line” , the initiative from former Google and NASA employees to build a 450 square meter underground park in an abandoned underground trolley terminal. Expanding on their indoor Lowline Lab which has had nearly 75000 visitors, the new initiative proposes the world’s first underground park, complete with a forest, water features, and plants.

“The Lowline’s skylight system uses external Sun-tracking parabolic dishes to gather and concentrate sunlight to 30 times its regular intensity. Internal optics filter out the hot rays, and the incoming sunlight is then distributed in a modulated way, to suit the vegetation – including exotic plants, mosses and hops. “Tropical species do best, but flowering varieties have also done very well,” says Barasch, one of the founders.

If approved, ten million dollars is needed for the investment and city approval. The goal for opening the world’s first underground park is 2021.