Silent film star Colleen Moore created this Fairy Castle in 1935 at a cost of $500,000 ($8m in 2015 dollars). It had luxurious amenities including a plumbing and electrical system. Tiny gold plates, crystal glasses and miniature needlepoint tapestries were custom made for the interior.
Moore donated it to the Museum of Science and Industry in Chicago in 1949. The Museum recently subjected it to a 9-month conservation with up to 5 conservators working 6 -7 days a week. See the castle being put back together by the conservation team in just 3 minutes in this time lapse video:
The conservators had to wear face masks when handling some of the tiniest objects to prevent inhaling them.
More: Mental Floss