Lord Malton's marble statue of Samson slaying Philistines is as large as life. That wine cooler from Burghley House, made of solid silver, weighs more than 200 pounds. John Singer Sargent's stately portrait of Charles, ninth Duke of Marlborough, his wife, Consuelo Vanderbilt, their two sons and their dogs (the dogs are Blenheim spaniels, bred on the estate since the 18th century) is nearly 10 feet tall. But the largest, most important object in "The Treasure Houses of Britain: Five Hundred Years of Private Patronage and Art Collecting" could not be brought to Washington. That object is, of course, the country house itself.

No exhibition here, no exhibition anywhere, has ever relied more on its installation.

Gervase Jackson-Stops, architectural adviser to the National Trust in London, and Gaillard F. Ravenel and Mark Leithauser of the gallery's design staff, who developed it together, confronted crushing problems:

How do you survey five centuries of shifting taste, especially when works of art from separated centuries -- a colossal marble foot of the 2nd century B.C., and an 18th-century bust -- bought at the same time, must be shown together? How do you evoke rooms from different eras -- Gothic, Jacobean, Palladian, Victorian -- in a single exhibition? And how do you arrange 835 vastly varied objects -- paintings "skied" upon the walls, one above the other, and Chinese beds and candlesticks, egg timers and earrings, marble statues, clocks, diamond-studded garters, soup tureens and sofas -- so that their display makes sense to the viewer?

They pulled it off.

It is true they had advantages. Some were financial. They were given lots of money; their installation cost more than $1 million, most of it from Ford, and they built their rooms from scratch. Some were institutional; the gallery's designers, under J. Carter Brown, are not merely given lists of objects to exhibit, they are brought in at the start and help pick the things displayed.

The gallery, additionally, has had a long relationship with the nobility of Britain. Its founder, Andrew Mellon, was ambassador to London; Paul Mellon, his son, who has built at Yale a museum for his British art, is well known to the queen; and John Walker, Brown's predecessor, is married to an English aristocrat. The seeds for the exhibit were sown long ago.

Recreated period rooms were ruled out at the start. A show from Woburn Abbey, say, might justify a detailed reproduction of Woburn's sculpture gallery, but some 200 houses lent objects to this show, and to fill that room with objects from Chatsworth or Petworth would constitute a lie.

Another path was chosen. The rooms to be constructed in I.M. Pei's angular East Building would be evocations instead of reproductions.

Consider, for example, the long Jacobean Gallery, the first set piece in the show. If its timbered ceiling soon feels eerily familiar, it is because it imitates the Arundel Castle ceiling seen over the right shoulder of the Countess of Arundel, whose early 17th-century portrait hangs there on the wall. The grotesque, and newly cast, lintel at the door is not from Arundel, but from Castle Ashby. The handsome leaded windows of greenish, hand-blown glass are copies from examples found at Hardwick Hall. And the window seats beneath them come from yet a fourth house: They imitate the seats that Leithauser discovered in a ruined wall at Kirby.

The Jacobean Gallery's painted walls are new, but you would not think so. Long and ancient cracks, imperfectly restored, crawl along their surfaces. Those plaster cracks were painted there by Washington's Dieter Pluntke. Pluntke can make plywood look like walnut, oak or marble. Surfaces so treated -- the team's term is "Dieterized" -- are found throughout the show.

The room is a pastiche. So, too, is the handsome chimney piece in the "Triumph of the Baroque" gallery nearby. Leithauser designed it after measuring examples at Beningbrough Hall, Boughton House and Chatsworth.

Throughout the exhibition, the chair rails and baseboards and decorative moldings have been similarly considered. So, too, have the wallpapers, most of them hand-printed from salvaged antique blocks. Some of them are yellow, some of them are blue, and some are crimson damask -- the same crimson damask on which Sir Joshua Reynolds displayed pictures at the Royal Academy. These details do not compete with the statue on the pedestal, the silver on the sideboard or the paintings on the wall. They perform their duties subtly. We sense rather than see them. The viewer seems to feel the centuries pass by as he wanders through the show.

The oval Sculpture Rotunda, with its skylight and its niches, is based, although loosely, on a gallery at Newby. A Nash design at Addingham inspired the columns and pilasters of the Waterloo Gallery, the grandest set piece in the show.

The intimate Dutch Cabinet takes its colors and its fireplace from Johan Zoffany's 1769 portrait of "Sir Lawrence Dundas and his Grandson in the Pillar Room at 19 Arlington Street." A 1654 seascape by Willem van de Velde appears above the fireplace just beyond the sitter; and seven statuettes are arranged on the mantel. If the viewer does a double take, it is because that seascape and all seven statuettes are displayed above the fireplace constructed for the show.

Not all its rooms are period rooms. Some, the Country House Library, for instance, are wholly uninflected and completely 20th century. Like the exhibition's lighting (designed by the gallery's Gordon Anson) and the colors on the walls, what one might call the show's intensity is varied. It rises and then falls and then intensifies again as one moves from room to room.

A number of the details do not come from Britain, at least not directly. In the yellow room devoted to "The Sporting Life," the decorative moldings are derived from Monticello. They were all cast from a bas-relief made by Leithauser 10 years ago while he was working on the gallery's exhibit, "The Eye of Thomas Jefferson." But then Jefferson, himself, had his moldings copied from Adam Brothers originals he had seen in England. So here, in this exhibit, they feel right at home.

Washingtonians who visit major art museums in London or in Paris, Chicago or New York cannot help but notice that the standard of installation maintained in this city, and not only by the gallery, is almost never matched. Ravenel and Leithauser and the members of their staff have accomplished much before -- think of their astonishing "Pacific Islands" show, of "Dresden" and "King Tut." The present installation does its objects proud. It is the best work they have done.

It does contain one inside joke. The neoclassical doorways that lead into the room devoted to "Lord Burlington and the Palladian Revolution" are almost exact copies of the Palladian doorways designed in the 1930s by John Russell Pope for the National Gallery's West Building.