Keith Haring sculpture stands outside the hall at the corner of 3rd and Howard streets. Moscone North is located to the north of Howard Street. Moscone West is a three-level exhibition hall located across 4th Street from Moscone North. Moscone North and South are connected by a pedestrian bridge over Howard Street, as well as by the underground exhibition hall, which extends far beyond the aboveground structures and beneath Yerba Buena Gardens and the Metreon entertainment center. The massive underground hall has been described as a bunker. Together, Moscone North and South have of contiguous exhibition space, two ballrooms, 82 meeting rooms, and of pre-function lobby space. A large solar electricity system was installed on the roof of the center in March 2004 by PowerLight Corporation. The installation of this system marked San Francisco's first major step towards obtaining all municipal energy from pollution-free sources. With the solar array (675 kW capacity) in place, San Francisco boasts one of the largest city-owned solar installations in the country. The electricity generated by the solar system, combined with savings from energy efficiency measures, delivers the equivalent energy to power approximately 8,500 homes. The location of the complex in the South of Market area provides easy access to downtown San Francisco's many hotels and restaurants, as well as major transportation systems. The center is two blocks away from the Powell Street station, which is served by both BART and Muni Metro. When complete, the Yerba Buena/Moscone station will also bring Muni Metro service to the southwestern corner of the convention center complex and provide connectivity with Caltrain. An Amtrak Thruway Motorcoach stop at Moscone Center (station code SFM) also transports riders to the Emeryville Amtrak station along the Capitol Corridor line. Labor organizations supported the construction of the center, and were granted full labor jurisdiction. All labor in the Convention Center is performed by I.A.T.S.E. Local 16 Stagehands, Sign and Display Workers Local #510, Brotherhood of Teamsters local #65, IBEW Local #6, Security I.A.T.S.E. Local #B-18, Communications Workers of America, and the Hotel & Restaurant Workers Local #2. IUOE Local #39 provides Engineering Services. Projection Presentation Technology is the on-site rental service. Events Moscone Center hosts many large events each year. During the 2016–17 season, Moscone Center hosted 74 events with a total attendance of 1,021,031. Moscone Center hosts a number of annual professional gatherings, including: American Bar Association annual meeting Dreamforce (since