The renowned Canadian architect Arthur Erickson, designer of the bold new Canadian Embassy that will rise on Pennsylvania Avenue across from the National Gallery, was awarded the Gold Medal of the American Institute of Architects yesterday.

Described by AIA officials as "the highest award the architectural profession can bestow," the Gold Medal was first given in 1907 and has gone to many of the great architects of the century -- Frank Lloyd Wright, Eero Saarinen, I.M. Pei, Ludwig Mies van der Rohe. This was the 56th time the Gold Medal has been awarded.

Though the prize most often goes to Americans, it has on several occasions gone to foreigners, such as the French master Le Corbusier.

Former Gold Medal recipient Philip Johnson said of the award to Erickson, "Arthur Erickson is by far the greatest architect in Canada, and he may be the greatest on this continent."

Erickson's firm is based in Vancouver, and much of his most ambitious work has been constructed there. His largest scale project yet to be completed is his massive, monumental Robson Square, a three-block reconstruction of Vancouver's center that includes the provincial government offices and courthouse, a media center and the Vancouver Art Gallery -- all set in a space of gardens and waterfalls.

The firm also has a branch in Los Angeles. Among his structures in the United States are the San Diego Convention Center and California Plaza in Los Angeles.

Reached late yesterday at his firm's Toronto office, a euphoric Erickson, 61, said, "I knew for some time I had been recommended. But I had only a very remote hope that I would be recognized, though it was a fervent one. And it comes at a wonderful time for me. After all, this is by far the most illustrious architectural award."

Erickson said he found out about it Sunday when his office phoned him to tell him. "I still can't quite believe it's true," Erickson explained. "I feel like going and hiding under a rock somewhere and gloating."

The award will be presented at the 1986 AIA convention in San Antonio next June.

The new embassy here, for which ground will be broken in March, will occupy one of the most conspicuous sites in the city: It will be the first building fronting directly on the north side of Pennsylvania Avenue as it proceeds west from the Capitol.

The design features an 88-foot cornice line on four sides to match the heights and scales of nearby structures. There are two principal fac,ades, one facing the avenue and the other facing a neighboring park, that are "eroded," in Erickson's term, to provide broad openings to a large outdoor entrance courtyard.

A particularly dramatic touch is a sharp corner lined up to be opposite the knife-edge corner of Pei's National Gallery East Building across the street.

Erickson's selection in 1982 for the embassy commission caused a stir in Canada. A bureaucratic committee had passed over Erickson, but Prime Minister Pierre Trudeau, a friend of the architect, overruled the committee.

Erickson said that in the design he approached the demands of the site "with great trepidation," both because of its particular prominence and because it was directly across from "two magnificent pieces of architecture."

"But it was an interesting challenge," he said, "because of the special restrictions Washington places on architecture, and I sort of welcomed it and went out of my way to do everything they say. I greatly admire Washington. It takes a lot of courage to set a building height and stay with it.

"In fact, the Washington style excited me. I suppose I have always had a touch of the classicist in me, despite my rather strict modernism. And this gave me a chance to use a few columns for a change."

AIA gave this description of the Erickson style: "lyrical, cool, classical, modern, neo-Inca, monumental and sometimes just breathtakingly beautiful . . . Though the forms of his buildings are often striking, his materials and colors tend toward neutral tones." AIA also referred to Erickson's "fascination with movement, place, route and destination . . . as in his Museum of Anthropology at the University of British Columbia in Vancouver, as well as at Robson Square."

Erickson's practice has been prolific, including the Canadian Pavilions at Expo '67 in Montreal and at Expo '70 in Osaka, Japan. He has designed a Sikh temple, two subway stations in Toronto, plans for a new town center in Kuwait, redevelopment of the Tigris riverfront in Baghdad, Iraq, two universities in Saudi Arabia, and a visitors' pavilion made of recycled newspapers for the 1976 United Nations Habitat Conference in Vancouver.

A native of Vancouver, Erickson received his architectural training at McGill University in Montreal, and taught at the University of Oregon and the University of British Columbia.

AIA gave this quote from his nomination: "He thinks in terms of human needs beyond the interpretations of any one culture."