The ballroom, built in 1929, is lavishly decorated in ornate Spanish Colonial style - features include an indoor fountain, curved 'Juliet' balconies, bronze chandeliers, highly decorative faux windows (backlit to simulate moonlight!) and ornate handpainted ceilings (pictured below). A little kitsch, but utterly breathtaking.
Incredibly, the Plaza Ballroom as it stands today is a complete restoration of the original, which was destroyed by fire in 1945.
I just discovered another lovely photo of the Ballroom, and a collection of very sneaky photos of the Open House Capitol Theatre tour on a blog called the grapevine. Read the text too - very funny!
Intricate decorative patterns on the ceiling (top image) and even in the carpet! (bottom image). Apparently parquetry flooring is laid over the top of this carpet when required. Big job!