The music-room of the King of the Beaver Fairies
Because apparently there are Beaver Fairies. And their King lives in an awesome castle and not just some pile of logs and mud.
John Dough and the Cherub was not originally an Oz novel, but John Dough and Chick the Cherub show up in the Emerald City of Oz for Princess Ozma's birthday in The Road to Oz (1909).
"At our banquet, this evening," said he, "I will permit you to see my people. But now please come to the music-room, where you may enjoy the strains of harmony that provide us with one of our chief amusements."
He led the way to another room, the roof of which was dome-shaped. From different points in this dome projected the ends of many silver tubes, and near the floor of the room, directly underneath each of the tubes, was placed a plate of glass or of metal.
The King invited his guests to seat themselves, and then pressed a diamond button that was placed in the wall. This allowed the water from the river above them to drip slowly through the silver tubes; and as it fell, drop by drop, on the plates beneath, it made sounds that were very sweet and harmonious. The metal plates gave out deep and resonant sounds, while the smaller glass plates tinkled melodiously as the drops of water fell upon them.
Neither Chick nor the Princess recognized the first tune that was played, for it had been composed by one of the Fairy Beavers; but afterward the King played "Home, Sweet Home," for them, and "Annie Laurie"; and the music was so exquisitely sweet and soft that the girl declared she would never have imagined that sounds so delightful could be produced, and Chick pronounced the entertainment "all right."
The ginger-bread man was also pleased; for it was the first real music he had ever heard, and it soothed and comforted him beyond measure.