Richard Haas would like to paint the shadows of the Empire State and Chrysler buildings on the north sides of the World Trade Towers. Or perhaps o build a "Light Top Connection" arching between the towers as "an aviary for eagles." These notions--pencil drawings on photographs--along with maquettes, photographs and etchings of completed projects are on view at The Octagon through July 18.

"Richard Haas: The Architecture of Illusion," is captivating. Haas disdains the "trompe l'oeil" label for his work, but these lithographs and etchings are guaranteed to at least intrigue if not trick the eye.

Haas is best known for a dozen outdoor murals he's done in the past few years, including the Art Deco Lincoln Tunnel exit, the Times Tower and the Dakota Apartment entrance in New York; the Beaux-Arts cross-section view on the back of the Boston Architectural Center, and "Homage to the Chicago School," on an apartment building on North LaSalle Street, Chicago. He's also finished eight permanent indoor projects, similarly relying on shadow, imagined classical designs and creative improvements on existing structures.

Haas finds humor in juxtaposing the new with the old, in painting over blank walls to perfect a vision of buildings past. For the facade of the Con Ed building in lower Manhattan he added to the actual view of the Brooklyn Bridge peeking over the roof a stunning arcade with another view of the bridge through a "cutaway" section.

It's a show of doubletakes, as you decode the illusions via before-and-after photographs. JOANNE OSTROW THE ARCHITECTURE OF ILLUSION -- Through July 18 at the Octagon, 1799 New York Avenue NW. Tuesday through Friday 10 to 4, weekends 1 to 4.