Work began in 1949 on a home for Julius Kruttschnitt II, then General Manager of Mount Isa Mines. He had come to the struggling field back in 1930, an American steeped in his country's mining industry, charged with reviving a venture that could barely meet its bills - and over two decades he had helped turn it around. The grand house was his reward and his statement. He brought in the prominent Brisbane firm of Donoghue, Cusick and Edwards, but the design carried the imprint of his own years in Arizona and Mexico: Spanish Mission style, built of six-inch Denaro bricks, U-shaped around a courtyard ringed by verandahs on roughly hewn timber posts. An annual New Year's Eve punchbowl party was one of the rituals the Kruttschnitts hosted within these walls.

Casa Grande was never meant to blend in. It stands on a rise, deliberately, a landmark overlooking the mine and the modest houses of the Mineside settlement clustered below. Around it spread well-kept grounds, an encircling drive, a tennis court, and gardens so luxuriant they seemed almost an affront to the arid country all around - greenery as a display of what the company could summon in a place where water was precious. The contrast was the point. The grandeur and elevation announced the social standing of the man who ran the mine, the distance, in every sense, between the manager on the hill and the workers in the valley.

When Kruttschnitt resigned as Chairman of Directors in 1952 he did not go home to America but settled in Brisbane, in another house he called Casa Ita. George Fisher succeeded him and lived at Casa Grande with his family until 1966, refurnishing the place - and much of that furniture remains today. After 1966 the house became a guest residence for visiting company directors and VIPs. The grandest guest came in 1970, when Queen Elizabeth II visited Mount Isa: a suite was redecorated and refurnished for her, and the company commissioned a dining table whose top was cut from a single piece of cedar. The 'big house' had risen, briefly, to host a monarch.

Casa Grande was built at a turning point. It went up just as Mount Isa Mines paid its first dividend, the company emerging from years of struggle into real prosperity; by 1955 MIM was the largest mining company in Australia, with an international reputation. The house froze that moment in stucco. Added to the Queensland Heritage Register on 28 May 1999, it survives in excellent condition, its later additions mostly sympathetic to the original design. To walk its grounds now is to read the social order of a vanished company town - the careful hierarchy of a place where the mine was everything, and where the man who ran it lived, quite literally, above it all.