The halls of Hillandale resounded last night to the sort of music and laughter the house was built for in 1921. Its builder, Anne Archbold, the legendary Washington explorer and grande dame, died in 1968, but anyone who was at the Decorators' Show House benefit preview there last night suspected she would have approved of the evening.

Back in the '20s, of course, a party on that scale, with several hundred guests, would have been a private event. But in the 1980s such an event is almost always a benefit. Last night's was organized by the Women's Committee of the National Symphony Orchestra, under the chairship of Christina Boldman and the patronage of the Ambassador of Luxembourg, Adrien Meisch, and his wife, Candace. With the diplomatic couple, the symphony benefit got both patrons and entertainers. The ambassador, who often plays with quartets, played the piano in the music room, and his wife sang. Candace Meisch said they take her husband's Bo sendorfer piano to all their diplomatic posts. The ambassador admired the acoustics of the 60-foot-long music room, but his wife said the wood paneling in the Luxembourg Embassy also makes for good sound.

Some 30 of the guests were interior designers who had redecorated 34 rooms of the house, which has been empty since its late owner, John Archbold, the son of Anne, moved out when the property was sold for a housing development. The house itself is up for sale for $3.5 million. The house will be open to the public beginning Sunday through Oct. 31.

Cristina Boldman said that some 500 guests attended last night's preview benefit. David Lloyd Kreeger, who has the grandest new house in town, admired Hillandale but said he liked the architecture of his own house better and didn't offer to swap. The house was originally designed by Josephine Wright Chapman, a Paris architect, in memory of the great Tuscany villas. The entrance to the house is appropriately up a hillside, although this one is covered with rowhouses, not vineyards.