For decades, a derelict powerhouse loomed over the banks of Brooklyn’s toxic Gowanus Canal, its mysterious halls hidden away and accessed only by intrepid teenage squatters, graffiti artists and urban explorers. Now, the doors to this historic structure, known as the Batcave, have opened to the public with the official launch of Powerhouse Arts on May 19. This 170,000 square foot arts fabrication facility connects the old Brooklyn Rapid Transit Power Station, a 119-year-old landmark, to a new six-story building designed by internationally renowned architects Herzog & de Meuron, with PBDW Architects.