The 100th birthday party of Grand Central Terminal is poised to be as grand as you would except it to be, with entertainment and activities for the whole family. Highlights include a concert by the West Point Brass and Percussion Band (9:30am) addresses from ex–poet laureate Billy Collins and former Mets first baseman Keith Hernandez (10–11:15am), and a replica of the terminal made entirely of LEGOs. Plus, tots with a groovy side can watch a performance by the Knicks City Kids dancers (1:50pm, 3:50pm) and boogie under that famous ceiling to live music by Rhythm Collective, and Vince Giordano and the Nighthawks (6:30–9:30pm). The event also marks the opening day of the New York Transit Museum's new exhibit, "Grand By Design," which explores the architecture and history of the iconic building. All ages.