Time Out says
The Lowline is an innovative city project that uses solar technology to illuminate a historic Williamsburg Bridge Trolley Terminal beneath the streets of NYC. Eventually, the Lowline will be developed into an underground park capable of becoming home to trees, plants and the work of talented architects and engineers; it's projected to fully open in 2020.
Currently, the Lowline Lab is open to the public and serves as an education and community space.
140 Essex Street