At the moment, they're just street corners and bus stops. But they could be happy, upbeat places--if Dickson Carroll has his way.

Both fantasy sculptor and practical architect, Carroll has finally combined his talents in his latest show at McIntosh/Drysdale Gallery.

Filled with small-scale models for architectural projects--turreted bandstands, glorious gazebos and throne-like benches with pagoda-like roofs--Carroll's fanciful new projects suggest that even sitting and waiting for a bus could be fun. Life at the beach could also be enhanced by his "Two-Story Gazebo," where privacy is insured by two separate ladders to two separate levels.

But though they exist in beautifully made models, all of the above are still figments of Carroll's imagination--unless, of course, someone decides to build one.

In fact, one project titled "Canopy Sculpture" is being considered by the Oliver Carr Co. for the corner of 18th and M Streets NW. This 38-foot-tall roofed pavilion with a seating podium would be built from steel and would serve as a magnet for flower-sellers, street musicians and people just looking for a shady place to sit, eat or read among the hubbub. It is the sort of structure that offers focus and lively meeting place in Mexican towns, but is wholly lacking here.

Carroll, a Yale-trained architect, began showing his fantasy sculptures a decade ago--biomorphic shapes carved from wood, painted in bright colors and topped with flamboyant curlicues, cupolas and fanciful weather vanes. Two examples still spread good cheer from the rooftops of the Sheridan and Murch Schools in Northwest Washington, and others offer private pleasures in Cleveland Park back yards. One "City Fantasy" was commissioned by the adventurous National League of Cities for its lobby at 1301 Pennsylvania Ave. NW.

"After doing fantasy sculpture for so long, it occurred to me that I could do projects that could actually be built," says Carroll. "They'd be expensive, and most are still imaginary in that I have no clients for them. But during the show, many people have expressed interest in the gazebos and benches as a neighborhood focus. I'm just shooting out proposals with the hope that clients will turn up." Others may well share that hope.

The show, though a happy one, marks an unhappy occasion--the closing of McIntosh/Drysdale Gallery, which is moving to Houston at the end of July, as reported earlier. The gallery will be sorely missed.

The show will be on view through July 30. Hours are 11 to 5:30 today and next Tuesday through Friday.Group Show at Henri's

Henrietta Ersham--better known as Henri, the longest-running dealer on the P Street strip--is having her last show at 1500 21st St. NW. Two years ago she was forced by her landlords to vacate the first two floors of the four-story building she had occupied in its entirety since 1967. Now, after a two-year legal battle, she has been told to vacate the third floor as well--by Aug. 15. After that, she will be allowed to retain only the fourth-floor space, which has been her home for 15 years.

Henri, who will be 74 on July 27, remains undaunted. "I will hold salons in my apartment until I can find new ground-floor space in a condominium nearby," she says. Meanwhile, she is painting her hallway purple while the outside of the building is being repainted black. "My landlord knows I'm not the beige type," she says.

Henri's final group show in the third-floor space is filled with the kind of quirky, offbeat art that has always been her specialty: a maddening chest of drawers that won't open, along with a tall wooden table covered with tiny yellow chairs that tumble in every direction--the work of improbable furniture maker Robert Booth--and a Booth sculpture made from an old porch pillar wrapped with miles of brightly colored thread. There are funny narrative sculptures by Lester Van Winkle, a luscious abstract painting by Tom Nakashima, and a small example of Frank Faulkner's rich, metallic-looking mixed-media work on paper. A Robert Stackhouse drawing, a new Cynthia Bickley landscape painting and a few of George Ikinaga's mysterious gray boxes round out a varied, first-rate group.

Henri's show will continue through Aug. 15, Tuesdays through Saturdays 11 to 6 and Sundays 2 to 6. 'Zenith Presents Zenith'

The 20-minute videotape titled "Zenith Presents Zenith," recommended to visitors of Zenith Gallery's current show, was produced by Marty Martin. The tape shows the working methods of five artists included in show--one of Zenith's best to date. The show and the tape are on view through Sept. 4 at 1441 Rhode Island Ave. NW.