Plan to make more than one trip to the National Gallery's exhibition of "20th-Century Masters: The Thyssen-Bornemisza Collection," a summer-long showing of dramatic modern paintings opening Sunday.

While only 66 in number, they represent the best of contemporary American and European artists -- "art you could live with," the Baron might say. Indeed, these are the works that line his private walls, unlike his renowned collection of Old Masters, stored in galleries attached to his Swiss residence. He's parted with these treasures for 18 months while the exhibit travels (to five other U.S. museums after leaving the East Building on September 7.)

The collection is installed in logical sections flowing from the gallery's upper level to the mezzanine. The expressionists' boldly colored, often idyllic works fill the first room. Included are Picasso's distorted "The Harvesters" and "Nude with Arms Raised," Maurice Prendergast's mosaic oil, "Autumn," and "London, Waterloo Bridge" by Fauve painter Andre Derain, borrowing from the Pointillists.

Abstractions are second, ranging from Kandinsky's spontaneous swirls of color to Mondrian's rigid "Composition in Red and Blue" -- boxed in red-black-white-blue without the yellow that was often part of De Stijl. Other abstractions are intellectual without losing the emotional element. Moholy-Nagy's "Large Railway Picture" conveys the feel of pulling out of a station in a traveler's trance, past the tracks, lights, signals, numbers, signs and gates in a collage-like oil. You can hear the locomotion.

Next are action-packed testaments to the dehumanizing aspects of the city. Urban nightmares by Max Weber, Georges Grosz, Lyonel Feininger and Frantisek Kupka take swipes at metropolitan madness and the industrial age. Kupka's "The Machine Drill" is a hugely complicated contraption of shiny gears and wheels, obscuring the tiny drill itself. Fernand Leger's "The Staircase" is a freeze-frame of molecular motion. Stairs appear in disjointed cylinders with an automaton (nude? descending?) in the center.

A grouping by the surrealist generation reveals the extent to which Marc Chagall, Joan Miro, Salvador Dali, Rene Magritte and others tapped into the dreamscape. Their imagery is sexual, existential, violent, even whimsical. Dali's images are wildly irrational yet perfectly realistic in the vocabulary of the subconscious in "Dream Caused by the Flight of a Bee around a Pomegranate a Second before Awakening."

Ten works by American painters include an uncharacteristic Georgia O'Keeffe, Richard Estes' realism in "Telephone Booths," and Robert Rauschenberg's pop photo-collage-silkscreen, "Express." Two by Arshile Gorky include "The Black Monk," found on his easel after he committed suicide.

Finally, the human figure is treated by Edward Hopper, Tom Wesselman and Ronald Kitaj, among others. Hopper's masterful "Hotel Room" reveals the loneliness of a young woman adrift. She sits on a single bed wearing only a slip and fingering a letter, her hat, shoes and luggage filling the impersonal room. Lucian Freud's "Large Interior, Paddington," is a disturbing portrayal of the human interior. A boy wearing only a t-shirt stares blankly at a plant, dreaming. But the man's coat hanging above and his ambivalent facial features, indicate the dreamer may be an adult. What would we expect from Sigmund's grandson?

In addition to offering a dazzling tour of some of this century's masterworks, the show and accompanying catalog make clear the relationships between the various art "movements." And imagine: this is what a single collector sees when he looks around his house. 20th-CENTURY MASTERS: THE THYSSEN-BORNEMISZA COLLECTION -- At the National Gallery East Building, Sunday through September 6.