The tour of Shangri La begins at the discreet entranceway, where my tour guide explains the rules. There are many.
A security guard will shadow us constantly. Don't take photos inside. Not all uncovered patio areas count as outside. If you need to go to the bathroom, a security guard will take you there, too.
It feels a little over the top, and results in some sniggering and raised eyebrows among the tour group. But then we go inside. And, my goodness, the house. The house is astonishing.
Ms Duke knew a thing or two, that's clear. She died in 1993, having assembled one of the most exceptional collections of Islamic art in private ownership in the world. It includes tapestries, carpets, mihrabs (prayer nooks) urns, mosaics, ceiling and wall panels, ceramics, glass and metalwork.
She assembled some 2500 pieces over her life of travelling and collecting.
Born in 1912, the child of American Tobacco Company founder James Buchanan, Duke fell for Hawaii on her honeymoon with husband James Cromwell - reportedly because the islanders left the famous pair alone.
The dramatic site on the south shore of Oahu, near Diamond Head, was bought in 1936, and the house finished in 1939.
Duke and Cromwell separated soon after, and Shangri La remained Duke's winter retreat and sanctuary for the rest of her life.
She decorated according to her eclectic taste, with a mix of priceless artefacts - the oldest, 8th century urns - and knock-offs. She wasn't beyond having a replica made to match something purchased on her travels, but invested heavily in the real thing too.
She also clearly appreciated the natural beauty in her setting. And she knew how to live.
In the lounge, a floor-to-ceiling window with views over the Pacific slides away into the floor, giving full access to the lawn. In the 1930s, the window glass for this feat of engineering simply wasn't available - so Duke installed an elevator window.
Outside on the grass, a wide sofa is outdoor seating for about 12 people, overlooking the 4.8m (16ft) deep salt-water swimming pool. The pool house, under renovation during my tour, is where Elton John stayed when he visited.
Duke also built her own harbour to moor her private yacht - which was commandeered during World War II. And, at the rear of the house, behind an unassuming white wall, is her place for quiet contemplation - a Mughal Garden, with formal planting and water features.
Unfortunately, we cannot end our tour with a wander down the immaculate lawn. Viewing is from the terrace only. Then the bus whisks us back out the gates.
CHECKLIST
Getting there: Air New Zealand flies daily from Auckland to Honolulu.
Visiting opulence: For tours of Shangri La, book through the Honolulu Museum of Art. There are three tours daily from Wednesday to Saturday. Tours take two hours and 30 minutes including travelling time from the museum. The entry price includes entry to Honolulu Museum of Art. Children under the age of eight are not permitted at Shangri La.
Further information: See gohawaii.com and DiscoverAmerica.com for more on visiting Oahu.
The writer travelled to Hawaii courtesy of the Oahu Visitors Bureau, Air New Zealand and the Outrigger Waikiki on the Beach.
