IN LESS THAN two months the Old Patent Office Building -- home since 1968 to both the National Museum of American Art and the National Portrait Gallery -- will close its doors for a renovation of the Greek Revival structure, including upgrades to the wiring, air conditioning, elevator and security systems. The last day that the Museum of American Art will be open to the public is Jan. 3, while the Portrait Gallery will remain open until Jan. 9.

During what is expected to be three years of construction, the museums will not exactly be hibernating, having culled from their vaults a series of nationally touring exhibitions. The NMAA's Renwick Gallery of American craft will also remain open here, highlighting in the Grand Salon works of art from NMAA's permanent collection.

In the meantime, here's the final fruit of the fall season:

Over at the National Museum of American Art, "Edward Hopper: The Watercolors" brings together a rare treat: 56 examples of this giant of American realism's plein-air sketches of New England, Mexico, South Carolina and Manhattan. Leaner and more spontaneous than his famous oils -- yet still betraying a virtuosic technique -- Hopper's watercolors from the 1920s, '30s and early '40s are mostly pictures of 19th-century buildings devoid of the people that animate his laconic masterworks.

They're set designs for plays that hadn't been written yet, the New England summer-home setting of a "Long Day's Journey Into Night" -- but without the Tyrone family in the picture.

If the oil-on-canvas "Cape Cod Morning" from 1950 is the finished drama -- with its sad, solitary female subject leaning into a bay window over a field of dry, yellow grass -- then a watercolor like Hopper's 1934 "House on Pamet River" could be its unpeopled equivalent: an empty, wind-swept stage lit by the same theatrical slant of sun on white clapboard.

There may be few actors but there's no shortage of feeling -- or movement -- in these otherworldly watercolors. Less polished than his canvases, Hopper's visions of the lonely homes and lighthouses of Gloucester and Truro, Mass., depict architecture whose stasis is contradicted by a subtle stirring. It's partly in the tension the artist is able to evoke between the old and the new, between the land and the sea, between light and shadow, that Hopper's buildings seem to lean into an unseen wind like sailboats -- earthbound vessels lifted straight out of a Winslow Homer seascape.

They're also stand-ins for the painter himself as well as metaphors for their absent occupants: people like lighthouse keeper Captain Joshua Strout, whose home is depicted in "Portland Head Light." Along the coast of Maine, Strout was known for for his legendary 1886 Christmas Eve rescue of the crew of a foundering ship. Despite the fact that none of that lore is made explicit in the painting, it tingles with subtext.

Hopper's watercolors are the ultimate in depiction, meaning that, unlike his studio paintings, he actually stood in the field and recorded what he saw as accurately as he could. Still, his genius lay not in the stories his houses tell but rather in the way their closed doors swing open to our dreams, imaginations and fears.

Is it any wonder where Alfred Hitchcock got his inspiration for Norman Bates's godforsaken house in "Psycho"?

An Edward Hopper painting.

It's little more than a long hallway leading up to the entrance of the Hopper show, but the "Sara Roby Foundation Collection" is worth slowing down for.

These 30 paintings and four sculptures -- a scaled-back version of the traveling show that spotlighted Roby's 1984 gift of art to the museum -- is less a meal than a plate of tasty tapas, but the carefully chosen pictures provide an object lesson in a slippery thing called "form."

At least that's what the foundation (founded in 1952) would have you believe, according to an early mission statement.

"Form," wrote board member Lloyd Goodrich, "is the fundamental structure, energy, movement and design of the work of art, as opposed to its more decorative or subjectively expressive qualities."

Forget all that though. Just watch how "form" wriggles out of one definition into another within the space of a single career. In 1925, the bloated, Botero-like figures of Yasuo Kuniyoshi's "Strong Woman and Child" were all about volume! volume! volume! Now, glance a few feet to the right at the splintered shards of flat color that limn the figures in the same artist's 1951 "Fakirs."

One artist, two pictures, many contradictions. (Are we having form yet?)

Henri Cartier-Bresson knows from form.

In his black-and-white portraits of the rich and famous, the poor and nameless -- 70 of which are now on view at the Portrait Gallery -- the photographer uses composition, not color, and light, not props, as a way to reveal character.

His pictures of Marilyn Monroe and Truman Capote, of Joe the trumpeter and two anonymous Mexicanas feel found rather than made. They not only define moments plucked out of a blur of living, but the blur as well. They reek less of dumb luck or exertion than a flash of grace.

"Let your step be velvet but your eye keen," the artist once said. "A good fisherman does not stir up the water before he starts to fish."

There is that sense of stealth in all of Cartier-Bresson's work, that sense that patience was sometimes all that was necessary to get the subject to reveal himself, as with the unguarded laughter of the Dalai Lama or Coco Chanel.

And then sometimes there is the sense that no eternity could ever wipe the world-weariness from the face of Ezra Pound, or the wry detachment from the face of Marcel Duchamp or the thousand-yard stare from the pale, pale eyes of Sam Beckett.

Alexander Calder, whose great, sculptural head rises into a mostly-empty picture frame, is poised at that precise thaw between a beetled brow and a mischievous grin.

The show covers 63 years, but it's often hard to date the photographs if you don't cheat by looking at the wall labels (or the tell-tale unfiltered cigarettes). Painters Pierre Bonnard and Lucien Freud were shot more than 50 years apart, yet they could be contemporaries . . . but in which decade? It's difficult to say.

Part of it is the boho timelessness of the art world. (It's there in Cartier-Bresson's portraits of Henri Matisse, Pablo Picasso, Saul Steinberg, Marc Chagall, Francis Bacon and others). But there's also more. When Cartier-Bresson took your picture, he wasn't documenting a moment in time any more than he was a physiognomy.

Rather they're like whole films reduced down to a single frame. When we look at one of these telling faces (whether it be a tired Martin Luther King Jr. or a sullen and still-Leonardo-DiCaprio-beautiful Capote), it's almost as if the artist was able to catch a fleeting glimpse of the shadow of his subject's own fate.

EDWARD HOPPER: THE WATERCOLORS and SARA ROBY FOUNDATION COLLECTION -- Through Jan. 3 at the National Museum of American Art.

TETE A TETE: PORTRAITS BY HENRI CARTIER-BRESSON -- Through Jan. 9 at the National Portrait Gallery.

Both museums are located in the Old Patent Office Building at Eighth Street between G and F streets NW (Metro: Gallery Place/Chinatown) and are open from 10 to 5:30 daily with free admission. 202/357-2700 (TDD: 357-1729) Web sites: www.nmaa.si.edu and www.npg.si.edu.

Public programs associated with the Hopper exhibition include:

Tuesday at 2 -- Video documentary: "Edward Hopper: The Silent Witness."

Thursday at 6 -- Lecture: "Hopper's Places and the Relativity of Realism."

Nov. 21 at 2 -- Lecture: "Watercolor and American Modernism."

Nov. 24 at 1 -- Discussion of the watercolor "White River at Sharon."

Dec. 7 at 2 -- Video documentary: "Edward Hopper: The Silent Witness."

Dec. 11 at 2 -- Video documentary: "Edward Hopper: The Silent Witness."

Dec. 12 from 1 to 3 -- Discussion and demonstration of watercolor conservation and restoration.

Public programs associated with the Cartier-Bresson exhibition include:

Monday at 12:30 -- Film: "Dr. Martin Luther King Jr.: A Historical Perspective."

Tuesday at 12:30 -- Film: "Bogart: Behind the Legend."

Thursday at noon -- Walking tour of the exhibition with curator Mary Panzer.

Thursday at 6 -- Film: "The Crucible."

Nov. 22 at 12:30 -- Film: "Casablanca."

Nov. 22 at 7 -- "Readers' Theater: Southern Accents." Dramatization of work by Katherine Ann Porter.

Nov. 29 at 12:30 -- Film: "Monroe."

Nov. 30 at 12:30 -- Film: "J. Robert Oppenheimer: Father of the Atomic Bomb."

Dec. 6 at 12:30 -- Film: "The Jilting of Granny Weatherall."

Dec. 13 at 7 -- "Readers' Theater: Southern Accents." Dramatization of work by William Faulkner.

Dec. 14 at 12:30 -- Film: "Dr. Martin Luther King Jr.: A Historical Perspective."

Dec. 16 at 6 -- Film: "The Misfits."

Dec. 20 at 12:30 -- Film: "Breakfast at Tiffany's."

Dec. 20 at 7 -- "Readers' Theater: Southern Accents." Dramatization of work by Carson McCullers.

Dec. 21 at 6 -- Film: "Truman Capote: The Tiny Terror."

Dec. 27 at 12:30 -- Film: "Monroe."

Dec. 28 at 12:30 -- Film: "J. Robert Oppenheimer: Father of the Atomic Bomb."

Jan. 3 at 12:30 -- Film: "Dr. Martin Luther King, Jr.: A Historical Perspective."

Jan. 4 at 12:30 -- Film: "Martin Luther King Jr.: The Man and the Dream."

Jan. 6 at noon -- Walking tour of the exhibition with curator Mary Panzer.

Jan. 6 at 7 -- "Scenes from Arthur Miller" (Part 1: "The Crucible").

Jan. 7 at 7 -- "Scenes from Arthur Miller" (Part 2: "Death of a Salesman").

Jan. 8 at 7 -- "Scenes from Arthur Miller" (Part 3: "All My Sons").

Jan. 9 at 7 -- "Scenes from Arthur Miller" (Part 4: "After the Fall").