Scarecrow's mansion
First named in The Emerald City of Oz, ch. 25
journeyed in sight of the Scarecrow's new mansion
As the books describe it
The Scarecrow's new house was shaped like an immense ear of corn. The rows of kernels were made of solid gold, and the green upon which the ear stood upright was a mass of sparkling emeralds. The Emerald City of Oz, ch. 25