A concert venue located at 17 Irving Place, near Union Square in NYC. It's on the corner of 15th street and Irving Place. You can get there by taking the 4, 5, 6, L, N, or R subway to Union Square 14th Street.
Irving Plaza is a 3 floor building. The bottom floor contains the lobby, lounge coat check, and bathrooms. A staircase leads to the second floor, which is a ballroom type dealie. The dance floor is about the size of a basketball court. Another staircase leads to the balcony, which is all standing room, although sometimes one side is velvet roped off and some tables are put in.
There is no age requirement, but you must be accompanied by adult if you're under 16. Although from my experience, they don't care.