Last Saturday afternoon, two hours after the show was to have opened, art dealer Chris Middendorf and his staff were still standing around in mittens and scarves, waiting for the crew from United Rigging & Hauling to finish hoisting, balancing and ultimately transforming six square, rusted steel plates (total weight: 9,000 lbs.) into two sculptures by Minimalist artist Richard Serra.

The six-man crew had been at it since 7 a.m., when three flatbed trucks and a 20-foot crane (total cost: $12,000) pulled up in front of the gallery and double-parked for the day. Ten hours later, the first cheers went up in the gallery as one 5-by-5-foot square slab of steel was balanced atop another in a T formation, and then propped against the corner walls for further support. The "prop" piece, titled "5 S Corner," at last was standing on its own, and someone broke out a jug of Folonari Soave.

By 5:30 p.m. the second piece, "Inverted House of Cards," also suddenly came to life as the last of four four-foot-square, half-ton slabs -- each standing on its edge and leaning against the next like a pinwheel-shaped house of cards -- was ever so carefully let go by its handler.

"Isn't that a beautiful piece?" enthused Middendorf, who had spent $6,000 to reinforce the gallery floor. "Gorgeous," replied his chorus. And everyone clapped and cheered and marveled at the skill and courage of the crew and at the steel nerves of artist Steve Ludlum, who had so fearlessly supervised the placement. "I have faith in universal things -- like gravity," he explained.

So, of course, does Richard Serra, 46, whose works' seemingly precarious tonnage (in fact, his works are very solid because of their weight) depends on gravity and appears at the same time to defy it. The solidity of "5 S Corner," for example, is very hard to believe in, and it appears to teeter perilously, as do all of Serra's "prop" pieces. The best of them, however, also seem to soar, as does the appropriately named "Kitty Hawk," a far more beautifully proportioned variation that greets visitors as they enter the new Saatchi Collection gallery in London. (Until very recently, Serra -- like Minimal art in general -- has been far more widely shown, appreciated and collected in Europe than here.)

Serra's intent, as he has said repeatedly, is to alter one's perception of space, including what he calls the "behavioral space" surrounding his sculpture. And when he succeeds, he charges the atmosphere with danger. He succeeded so well in the case of his controversial "Tilted Arc," which stands on the plaza of the Jacob Javits Federal Building in lower Manhattan, that the people who use the building are insisting that the sculpture be removed because it has changed their once peaceful space in a way that is definitely not to their liking. Another public piece in St. Louis, titled "Mark Twain," is similarly under attack.

"My sculptures are not objects for the viewer to stop and stare at," Serra said recently. And, to be sure, simply standing and looking at his work -- as one does with traditional sculpture on a pedestal -- may yield nothing whatsoever. One must submit to it, try to experience it in a visceral way, and in a successful piece like "Tilted Arc," the vibrations will inevitably come through.

For anyone who hasn't experienced "Tilted Arc," by the way, Middendorf has brought a smaller but clearly related piece to Washington and has installed it on the corner of 20th and Wyoming streets NW, just a block away from the gallery. The untitled piece is a free-standing arc that leans forward, toward the street, at an angle that seems menacing enough to scare away intruders. Another piece also has been sited at this location: a rather friendly-looking pair of rectangular solids -- friendly, that is, compared with most of Serra's minimal emblems of the age of anxiety.

Of the four pieces in this show (two outside, two inside), only "Inverted House of Cards" dates from the Minimalist heyday of the '60s, 1969 to be precise. Apart from being "vintage" in that respect, it is also handsome, strong yet almost playful in the way it transmits, through minimal means, an awareness of the elemental force of gravity and the artist's desire to manipulate it by toying with opposing weights and balances. It is these forces that give form to Serra's art.

There has been, in the past year or two, a revival of museum and gallery interest in Minimal art and, with it, an important opportunity to reassess, one by one, artists like Serra whose individuality was largely submerged when the Minimalist ship went down more than a decade ago. Middendorf's show -- a bold and outrageously expensive enterprise -- is, in fact, timed to coincide with the first American retrospective of Serra's sculpture, which will open at the Museum of Modern Art in New York Thursday.

Floyd Watkins, who headed the crew from United Rigging & Hauling, said he was put off at first by Serra's sculpture. "But after working with it for a while, I've gotten to like it," he said. Others undoubtedly will do the same. The Middendorf show will continue at 2009 Columbia Rd. NW through March 22. Hours are 11 to 6 Tuesdays through Fridays, 11 to 5 Saturdays.