It is called Mount Alto, yet the tree-lined, residential area around the National Cathedral has always had name troubles.

Because it is the highest point in the city, Mount Alto has been called Mount Altitude by jokesters for years. The official city map thinks it's part of Cleveland Park. Many Georgetowners simply call it "that place up the hill."

But now, like the famous knoll in San Francisco, Mount Alto can rightfully be called Russian Hill. For the Russians are coming, and neither the neighborhood, the feelings of some residents nor relations between the U.S. and U.S.S.R. will ever be the same.

What is on the way - in stages over the next four years - is a new Soviet Embassy complex.

The complex will sit on a 12.5-acre plot just northwest of Wisconsin Avenue and Calvert Street NW, where the Mount Alto Veterans' Hospital once was. It will consist of an eight-story chancery, an administration building, a nine-story apartment house housing about 1,000 people, a school and a gymnasium. Its cost is estimated at $70 million.

The complex will allow the Soviets, who have the largest foreign diplomatic contingent in Washington (500), to centralize their diplomats and diplomacy in one place.

At present, the Soviet Embassy at 1115 16th St. NW houses about half the Russian personnel and office space in Washington. Russian cultural affairs are handled from leased space on 18th Street, military affairs from a house on Belmont Road, visa inquiries at a house on Decatur Street. Diplomatic personnel live everywhere from Fairfax to Hyattsville.

The Soviets have wanted to move, expand and consolidate for more than 15 years. But to do that, a treaty had to be negotiated with the United States government, which has wanted to expand its Moscow embassy since the 1930s, according to the State Department.

The treaty was negotiated in two parts - one signed in 1969, one in 1972. Under the terms, each country leased land for 85 years in the other's capital for new embassy complexes. The complexes were to be built and opened simultaneously, so that neither nation would get a jump on the other in terms of facilities or morale.

But it hasn't worked out that way.

Construction on the Mount Alto embassy began last August. According to a Soviet Embassy press spokesman, an official of Bethesda's George Hyman Construction Company (the general contractor) and individual construction workers at the site, everything is going smoothly and according to plan.

Along the banks of the Moscow River, however, the 11.7-acre site designated for the new $100 million U.S. Embassy complex is nothing but a vacant lot.

Utility lines have been extended to the edge of the property. Trees and shrubs have been cleared. The site has been fenced off. But construction has not begun, and it will not begin in the foreseeable future.

The reason is that State Department officials and the Soviet government have not been able to agree on a construction contract. According to bruce Wormley Clark, deputy assistant director of the foreign buildings operations section of the State Department, the contract may not be negotiated until next spring.

"We feel the Soviets, for whatever reasons, are dragging their feet," Clark said. "We've had to repeat ourselves many, many times on the simplest, most basic things . . . I've done a lot of negotiating with labor unions, and they're beautiful compared with these people.

Clark stressed, however, that it would be incorrect to conclude that the Soviets are "getting ahead" in any race to finish an embassy.

The building now under construction at Mount Alto are the school, the gymnasium and the apartment house. The Soviets were given permission to begin these in a protocol signed in March 1977. Permission has not been given to begin the chancery and the administration building and will not be given, Clark said, until the way is clear for American construction in Moscow.

But even when full construction finally begins in both cities, the Soviets will enjoy an apparent advantage.

The Mount Alto site will be accessible from both Wisconsin Avenue and Tunlaw Road and will be away from congestion and most rush hour traffic.

In addition, because of its height, the site affords the Russians an excellent opportunity for electronic surveillance of federal government offices. No buildings would block a radio signal beamed from the upper floors of the chancery at either the Pentagon or State Department. While trees block a direct view of it, the Vice President's residence is half a mile away.

Soviet Embassy spokesman George Mamedov scoffed at the notion of surveillance. But Chester Sturm, the Advisory Neighborhood Commissioner for the Mount Alto area, said his constituents, who "read the newspapers," have "been concerned" about the effects of Russian electronic equipment on both their health and their television reception.

Meanwhile, the site of the new American Embassy in Moscow is one of the lowest pieces of ground in that city. The American complex will be hemmed in on three sides by apartment houses, and the only entrance will be from busy Chaikovska Street.

Clark said the State Department considered a higher, less cluttered site in the Moscow suburbs, which he said the Soviet government would have approved. But the U.S. finally decided that the Moscow River site, a mile and a half from the Kremlin, would be more convenient.

At Mount Alto, despite the presence of 400 Hyman construction workers each weekday, Soviet officials are firmly - if sometimes invisibly - in command.

Although there are dozens of copies in English, the main building plans are said to be written in Russian and kept under lock and key. Soviet security guards in blue jeans and hard hats routinely evict curious visitors.

Hyman officials refer all inquires about the project to the Russians. But the Russians refer inquiries right back to Hyman. The Russian "consulting engineer" in charge of the project, Boris Illiaronov, hung up four times on a reporter who called to ask for details of the project.

As far as most residents of the neighborhood are concerned, however, the new embassy will be welcome.

Majorie Davidson, who lives on Edmunds Street, just north of the construction site, said it will be "interesting" to "live near foreigners - and these aren't just any foreigners."

Janet newcastle, who said she has lived on nearby 38th Street for 41 years, said she is more worried about the recent conversion of a nearby apartment house to a Holiday Inn. "That will bring more traffic on Wisconsin Avenue than the Russians," she said.

Mary Lampson, an aide to City Council member Polly Shackleton, who represents the area, said only two complaints have been filed with Shackleton since construction on Mount Alto began.

One caller complained of noisy evening construction. The other complained of mudslides onto Tunlaw Road from the construction site. Hyman officials quickly settled the trouble both times, Lampson said.

One complaint that has dogged the Russians for years should vanish as soon as Mount Alto is finished.

Throughout the '60s and '70s, the Russians have been among embassy leaders in unpaid parking tickets. Most of the Russian tickets have been issued along busy 16th Street, in front of the present embassy. But at Mount Alto, all parking will be off-street and on-site.

"In general," said ANC representative Sturm, "we'll let them do their thing and we'll do ours."

One group that will be doing its thing elsewhere, however, are the hundreds of birds and dozens of varieties of wildlife that used to inhabit the Mount Alto site.

According to Charles Williams, executive director of the Washington area branch of the Audubon Naturalist Society, no complaints have been received or lodged about disruptions to Mount Alto wildlife. "But any time wooded ground is cut away, wildlife suffers," Williams said.

The Russians have removed hundreds of trees from Mount Alto in the last year. But that was part of the environmental impact statement they filed in 1975 with the National Capital Planning Commission. The commission approved the plan.

So Mount Alto, always topographically above the battle in Washington, will now, in a sense, be drawn into it. And just south of the embassy site, along Wisconsin Avenue, the surest sign of cultural overlap is unfolding.

In the late afternoons, at a series of bars, construction workers from both sides of the Iron Curtain sit down to drink. Vodka, the bartenders say, is outselling beer 3-to-1.