Though it was the better parts of two centuries aborning, the National Theater of Great Britain is, architecturally speaking, well into the 21st century, its slabs of concrete as coldly aggressive as the new east wing of the National Gallery in Washington.

What matter more than the National Theater's fortress-like aspect, however, are its auditoriums and stages. The Oliver is the jewel of the three, with 1,160 sharply raked seats, fanshaped, sweeping down to an accommodating thrust stage. The effect is not unlike that of Canada's Stratford and superior to the Kennedy Center's Eisenhower, which has 58 fewer seats. The Lyttleton has 890 seats and a traditional proscenium stage. The 400-seat Cottesloe, of the "black box" school, can alter playing areas for its programs of experimental plays.

The Oliver does honor to its name. As I admired its advanced, basically Grecian form, I recalled taking Laurence Olivier into the then-unfinished Arena Stage in Washington. Aghast at its rectangular playing area, Olivier proceeded to act out some of his great roles for me, coming to the highlights with his back to me.

"How can anyone act in central staging?" he asked.

Not for nothing is Lord Olivier the great actor. In the 17 years since he adapted himself to 21st-century stages, first at Chichester, later as the leader in the National Theater's creation.The sweeping intimacy of the Olivier reverses the concrete chill of its outer box. In comparison, the Kennedy Center is warmer, more assured and inviting, and infinitely less secretive.

The Queen's Silver Jubilee is the most dramatic event of England's summer, and presently the London stages can't match the Royal's crowd-exciting performances, which will continue through the summer.

Yet, with all three stages lighted for the first time, the National Theater is a must stop for all visitors. The unfamiliar plays include a new one from Robert Bolt, "State of Revolution," a detailed study of Lenin; Odon von Horvath's forgotten "Tales from the Vienna Woods" and a revival of Harley Granville Barker's "The Madras House." Far its best is Peter Hall's staging of "Volpone," with Paul Scotfield glorious in the title part and John Gielgud and Elizabeth Spriggs as the grasping Would be couple. This "Volpone," the finest staging I've seen in three weeks, will be in repertory through August and rates first on any list.

Stratford's Royal Shakespeare company continues in its London home, the Aldwych, with "The Comedy of Errors," "A midsummer Night's Dream," "Much Ado" and "Romeo and Juliet." Donald Sinden's Lear, one of the role's most stirring interpretations, has just ended, but he heads a company which also includes Judi Dench.

Once accents these subsidized companies because their personnel and facilities are more lavish than commercial managements can muster, though the subsidized managements moan about budget cuts.

There are the commercial hits of the traditional West End. John Mills heads a starry revival of Terence Rattigan's "Separate Tables." Rattigan has a new one coming in, "Clause Celebre." "Side by Side by Sondheim" continues with a substitute cast at Wyndham's while the original sells out in New York. The Haymarket, going back to 1720, has a rich revival of Maugham's "The Circle" starring Googie Withers. Robert Morley packs them into the Savoy for an old Ben Travers farce, "Banana Ridge." When the newly arrived Ambassador Kingham Brewster decided to take his guests, Chip and Caron Carter, President Carter's son and daughter-in-law, for his first trip to the theater, he chose "Donkey's Years," a farce with a Cambridge University setting not unlike his own recent Yale's.

From the Royal Shakespeare Company, "Wild Oats," a 1791 comedy by John O'Keefe, has moved to the commcercial Picadilly. After involved exposition, this settles into a vein of broad humor, offering a showy part for Alan Howard. Its major attraction of thearical conventions is not likely to attain the success of those recent RSC exports, "London Assurance" and "Sherlock Holmes."

William Douglas Home, who gave the Kennedy Center "The Jockey Club Stakes" and "Lloyd George Knew My Father," has had four plays this season, sharing with Alan Ayckbourn the title "most active playwright."

His hit is "The Kingfisher," starring Ralph Richardson and Celia Johnson as a couple reunited 50 years after he first proposed. They lie down under the same old tree and can't get up. There are beautifully allusive lines: "Coleridge had a maid . . . She berged in and scuttled Kubla Khan." This would play well in America's most civilized cities, though that does exclude New York. One though of what fun the Lunts would have in it.

Home's "Rolls Hyphen Royce," more like a projected movie script about the automobile firm, didn't for London despite all Wilfrid Hyde White's charm as the hyphen.

Ayckbourne's "Just Between Ourselves," on Sharfsbury Avenue, is far less box-office oriented than his "Bedroom Farce," in the National's Lyttleton, illustrating the commercial area's distrust of subsidized theater.

There are familier American hits, "A Chorus Line" at historic Drury Lane at half the New York prices but viewed as high in London. There are the original London versions of "Otherwise Engaged," "Equus," "Dirty Linen" and "Jesus Christ Superstar" and "Let my People Come." There's more erotica from Tynan's followup to "Oh, Calcutta," "Carte Blanche."

"Fringe" theaters thrive from noon to midnight. At the Roundhouse, where steam engines once were shifted around, there is now Tennessee Williams' "The Red Devil Battery Sign," which folded in Boston before it could reach the National last summer.

Rewritten and clearly improved, this has the best male role Williams has yet achieved, a Mexican father and lover dynamically played by Keith Baxter, who knows a good role when he reads one and also codirected. Williams' nymphomaniacal heroine has become a caricature. Why doesn't he let her age a bit and find a fresh viewpoint? If this does move to the West End as producer Gene Persson aims, it's still not ready for the ages, though the bones are there.

The Old Vic, spasmodically occupied since the Natioanl Theater opened its own home, again becomes a highly regarded home for the classics presented by the 14-year-old Prospect Theater Company. Eileen Atkins is Saint Joan, Derrick Jacobi is Hamlet and Timothy West stars in a new version of Homer, "War Music," by Christopher Logue and Donald Foster, well worth a visit.

Finally, there are Jubilee theatrical exhibits, with the old Covent Garden markets eventually to inherit aspects of several for permanent exhibit.

Most worth finding is the Victoria and Albert Museum's "The Royal Box," a fascinating record of past and present Royals from Elizabet I through Elizabeth II. The museum's record of "royal occasions in the theater" will continue until Oct. 2. From Brompton Road to the South Bank, from Morris Dances in Westminster Abbey and Shakespeare in St. George's, there's plenty to keep theatergoers hustling.