“Gay Day” at Hillwood features everything matrimonial as well as fun for kids. It’s this Saturday at D.C.’s fabled estate, museum and gardens.

“Where fabulous lives” is rightly the tag-line for the 36-room mansion, nestled on 25 acres encircled by woods and with 16,000 art objects from Faberge Easter Eggs produced for the Russian Imperial Court to Beauvais 18th-century French tapestries to Sevres porcelain.

But on Saturday from 10 a.m. to 6 p.m., Hillwood — a decorative arts museum and the former home and gardens of Post cereals heiress Marjorie Merriweather Post — will come alive with morning activities for LGBT families with their kids and in the afternoon with festivities specially keyed to same-sex couples contemplating getting married in D.C.

“We are thrilled to celebrate the newfound right of hundreds of couples who can now legally marry in D.C.,” said Hillwood media relations head Lynn Rossotti, “so this year we’ve added new wedding-themed elements to make Gay Day at Hillwood new for this year.”

According to Rossotti, marriage-related events include “punch on the portico styled like a wedding reception, story telling about marriage equality and a community bulletin board to post pictures, thoughts, quotes, wedding vows and tips. The D.C. Lambda Squares will also lead square dancing and Broadway love songs will be performed by the Rock Creek Singers of the Gay Men’s Chorus of Washington.

The morning begins on the mansion’s south portico with a family garden party co-hosted with Rainbow Families and includes breakfast treats, a performance of “Royal Russian Adventures” by Adventure Theatre, an “imagination station” (featuring books, games and fancy dress-up) and Russian wedding gown arts activities, followed by tee time on the estate’s putting green.

Afternoon festivities switch gears beginning with three gallery talks — at 12:30, 1:30 and 2:30 p.m. — by curator Howard Kurtz about Mrs. Post’s wedding dress from her 1958 marriage to Herbert May. At 1 and 3 p.m., D.C. Lambda Squares will lead square dancing. At 2 and 4, Speakeasy D.C. will present three storytellers that Rossotti called “real people who will share their personal stories about what marriage equality means to them.” At 2:30 and 3:30, the Rock Creek Singers perform.

From 4 to 6 p.m., participants can enjoy a wedding-style reception with hors d’oeuvres and punch on the mansion portico, with floral displays and a reproduction of a feature of the Post-May wedding, that Rossotti called “a gazebo-May pole with carved wooden poles surrounding a table for refreshments with its very mid-century ‘retro’ look of the 1950s era.”

Vintage cars will also be shown throughout the afternoon by the Straight Eights Region of the Lambda Car Club. And four rooms not usually open to the public — including Mrs. Post’s private napping room, called the “Snooze Room” — will be shown by interpreters.

Since 2001, Hillwood created an advisory committee of area LGBT leaders and has stressed outreach to the LGBT community, hosting past “Gay Day” annual events and summer outdoor film classics. Hillwood received an “Ally of the Year” award in 2007 from the Capital Area Gay and Lesbian Chamber of Commerce. This year’s “Gay Day” is co-sponsored by Spectrum Printing and Graphics and ACKC — Artfully Chocolate Kingsbury Confections.

Hillwood’s estate and gardens house one of America’s premier art collector’s museums in the U.S. Built in the 1920s on a wooded spot overlooking Rock Creek Park to the east, Post acquired the estate in 1955 after her divorce from her third husband, Joseph E. Davies, a wealthy investor and Franklin Roosevelt’s ambassador to the Soviet Union (1937-1938).

Admission fees for the “Gay Day” special family hours from 10 a.m. to noon are $12. From noon to 6 p.m., admission is $12 ($10 for Hillwood members), $7 for college students. There’s no charge for children and teens under 18 all day.

Hillwood is at 4155 Linnean Ave., N.W., about one mile north of the National Zoo, above Tilden Street between Connecticut Avenue and Rock Creek Park.