The 3.5 million square foot multi-use hospitality development incorporates energy efficient systems, occupancy comfort and wellness-minded material selection, preferred parking spaces for electric and high-efficiency vehicles, and emphasis on several technologies and innovations to manage water-making MGM National Harbor a premier, environmentally sustainable urban destination. The casino is wide open, slots are very crowded though. Amazing how they were able to mix Vegas with DC in this amazing building. Rooms are beautiful and views are all open. Comfortable and not over the top type of nice. MGM National Harbor integrates environmentally responsible practices, effectively lowering the carbon footprint of its operations across the resort. Busy time at MGM National Harbor but staff handles things great. MGM National Harbor features a 23-story, 308-room luxury hotel with amenities including fine dining from local and celebrity chefs, world-class entertainment, luxury retail shops, a three thousand-seat theater and a resort spa. Designed in collaboration between MGM Resorts International, SmithGroup as the architect of record and design architect HKS, Inc., MGM National Harbor opened in December 2016 on the shores of the Potomac River just south of Washington, DC in the National Harbor development. MGM National Harbor was designed to be an entertainment destination for the D.C.-metro region with over 15 dining options, 27,000 sq.