After the success of Chelsea's High Line, a couple of Lower East Side entrepreneurs are looking to transform an old underground trolley terminal into a sun- and plant-filled green space for the downtown set. The Lowline Lab, located in a shuttered food market, is their first public experiment in bringing sunlight below street level. To do so, they'll use solar collectors on the roof to let the sun shine through a "solar canopy." Visitors to the lab, which is open on Saturdays and Sundays through March 2017, can take a warm, indoor stroll among the more than 3,000 plants on display, which designers are testing for the future Lowline, planned for construction beneath nearby Delancey Street. For more info, visit thelowline.org.