The Hillwood Estate, Museum & Gardens. (Hillwood Estate, Museum & Gardens)

On a 1948 trip to Venice, cereal heiress Marjorie Merriweather Post, one of the wealthiest women of her day, picked up a carved and gilded eight-foot antique Bavarian ceremonial sleigh to add to her vast stash of treasures.

The German sleigh never found a real home in Post’s world-class collections of Russian Imperial and 18th-century French decorative arts, and it spent decades in storage. But on Wednesday, the Hillwood Estate, Museum & Gardens, Post’s Northwest Washington property that became a museum in 1977, is selling the sleigh (estimated at $3,000 to $4,000) at Doyle New York as part of a rare 70-lot de-accession of Post furniture, decorations, paintings and odds and ends.

The stuff comes from a good family. Some of the items were part of the personal collection of Post’s father, C.W. Post (1854 to 1914), founder of Post cereals, which eventually became General Foods. The rest belonged to the glamorous Marjorie (1887 to 1973), famous for her lavish parties, well-staffed houses and, of course, fine furnishings and collecting.

“This is a great opportunity to own something that has an interesting provenance and was part of the story of important American people,” said Liana Paredes, Hillwood’s chief curator. Paredes said the pieces to be auctioned have been in long-term storage with little hope of being displayed: a medieval Italian suit of armor ($1,000 to $1,500) , a pair of 18th-century stools from Post’s private dressing area ($1,000 to $1,500), a George III-style mahogany dumbwaiter ($200 to $400), a replica of the Canterbury Cathedral bells ($800 to $1,200), two pairs of nesting tables bearing the Post family crest ($200 to $250) and a Roycroft Arts and Crafts bedroom suite ($20,000 to $30,000).

The items are on display at Doyle’s New York showroom until tomorrow and will be sold Wednesday as part of Belle Epoque, an auction of 19th- and 20th-century decorative arts. Only a handful of things from Hillwood have ever been deaccessioned. “This is really a once-in-a-lifetime opportunity,” said Reid Dunavant, senior vice president and director of Doyle New York’s Washington office. He, by the way, said his favorites are the eight Louis XV fruitwood and raspberry-silk chairs ($3,000 to $4,000), part of the original 30 that Post bought for Hillwood’s glittering dining room. “Buying them would be the only opportunity you would get to sit in these chairs.”

A portrait of Marjorie Merriweather Post at the Hillwood Estate, Museum & Gardens. (Hillwood Estate, Museum & Gardens)

Though some local arts institutions are struggling, Hillwood officials say the decision to put the pieces up for auction was not financially motivated. “A couple of years ago, we started evaluating everything. These items were just sitting in storage,” said Lynn Rossotti, spokeswoman for Hillwood. “We have a lot of things [that are] important for research and exhibition value. But some are redundant and are not Russian or French.”

Rossotti said 2012 attendance at Hillwood was a record-setting 74,624, a 16% increase from 2011. (Over the past five years, museum attendance has increased almost 69%.) The endowment is currently at $190 million “and funds approximately 86% of our annual operating budget,” Rossotti said. “The proceeds from the auction will go into a fund only to be used for future acquisitions.”

Paredes said most of the pieces had never been exhibited. Some were part of C.W. Post’s collections in Battle Creek, Mich., while others furnished Hillwood’s third-floor guest and staff rooms before they were turned into textile and conservation labs. There are a few paintings and sculptures in the group. But Paredes said “most of these pieces were really furnishings, not considered works of art.”

The museum is continually searching for ways to connect with contemporary audiences. In 2007, it ramped up its marketing with the cheeky tag­ line “Where Fabulous Lives.” In 2011, the “Wedding Belles” exhibition drew crowds dying to catch a glimpse of the society bridal fashions and accessories worn by Post family members from 1874 to 1958. (There were plenty of elegant bridal gowns to show: Marjorie was married four times, and her three daughters all had multiple nuptials as well.)

The Hillwood cafe has been upgraded, the orchid program expanded, the gardens manicured and the greenhouses refurbished. Hillwood now hosts an annual Halloween dog-costume contest (Post loved her pooches and has a pet cemetery on the premises) and a film program named for the heiress’s youngest daughter, Dina Merrill. Their new focus on the fabulousness of the place has garnered them a new generation of devotees and raves on the TripAdvisor Web site.

A recent exhibit, “Pret-a-Papier: The Exquisite Art of Isabelle de Borchgrave,” drew crowds who were dazzled by historical haute couture made of crumpled, pleated and painted rag paper, some pieces interpreting Post’s own apparel.

Curators are currently putting finishing touches on an exhibit opening June 8: “Living Artfully: At Home with Marjorie Merriweather Post.” It’s a behind-the-scenes look at her collecting, entertaining and glam lifestyle at three of her estates — Mar-A-Lago in Palm Beach, Camp Topridge in the Adirondacks and the 25-acre Hillwood. It will also include a display of artifacts from the Sea Cloud, Post’s legendary 300-plus-foot sailing yacht. The exhibit will offer museumgoers a look into the 1950s and 1960s world of Post — as seen through the eyes of guests, family and the extensive staff that made the balls and house party weekends happen.

One of Hillwood’s curators has already dubbed it “ ‘Downton Abbey’ meets ‘Mad Men.’ ”