MANAGUA, Nicaragua (AP) _ A recent movie showed an airliner coming in for a landing at Managua. Below was a city crowded with skyscrapers, a teeming metropolis.

The scene was filmed somewhere else. Managua isn't like that. Its heart was destroyed by an earthquake 13 1/2 years ago and it largely remains that way, with squatters living in the ruins, like survivors of some sort of holocaust.

About 100 buildings, including the nation's largest Roman Catholic cathedral, are still the skeletons they became when the earthquake destroyed about 600 central blocks Dec. 23, 1972, killing more than 10,000 people.

The pyramid-shaped Hotel Intercontinental that once housed the reclusive billionaire Howard Hughes is one of the buildings that still stand here and there. But buildings that once housed businesses, shops and doctors' offices lie in rubble.

A dozen tanks and armored personnel carriers used by the Somoza government in its losing battle against the Sandinista guerrillas in 1979 lie rusting in a lot overgrown with weeds. Anti-American and revolutionary slogans are painted on most walls. A colorful block-long mural depicts, among other things, a figure representing death cloaked in an American flag.

Cars rush past the devastated downtown area on wide thoroughfares. There is no traffic on the cracked, pot-holed side streets that now go nowhere.

Some of the downtown has been converted into parks, but probably because few people live or work in the area, they are largely deserted and ill-kept.

Instead of being a nucleus for the city, the downtown area is a void. The heart of Managua has been removed and no one has put another one in its place.

Although the leftist Sandinista government says it has big plans to build a new downtown and some tentative steps toward revival have been taken, it will be at least a decade before construction begins on a large scale, according to Fernando Morales, a city planner.

The project has a low priority for a government that is fighting U.S.-backed insurgents in a war that reportedly eats up at least half the national budget. The economy here never had recovered from the revolutionary war that ousted Anastasio Somoza from the presidency in July, 1979.

But the government and private business have made some improvements, mostly near Lake Managua where there now is a promenade.

From the ruins of what used to be a medical laboratory, Guillermo Campos can hear hammers pounding as construction workers a block away restore a government office building.

City planner Morales said in an interview it is one of three that have been or are on the way to being rebuilt by the Sandinista government. The government also has filled several flattened city blocks with low-cost, two- story townhouses, which are mostly occupied by government workers.

Campos, a night watchman for a restaurant, has lived in the concrete shell of the laboratory for four years with his wife and six children.

''I hope the government does not remove us so it can rebuild this house,'' Campos told a visitor. ''Right now it is calm here. There are no problems.''

In place of curtains on his bedroom window, Campos has stacked chunks of concrete onto the ledge. Large sections of the walls and part of the roof have tumbled down, as if the building sustained heavy bombardment. Two chickens strut along the dirt floor.

From the roof of the building, Campos pointed out neighboring ruins and said they are all occupied by squatters. A half-dozen women washed clothes at an outdoor water faucet a half-block away, the only source of water for the neighborhood.

About 10 minutes' walk from Campos's house, workmen are building a discotheque next to a popular steakhouse called Los Antojitos.

The manager, Edgar Garcia Ponce, said Los Antonitos, across the street from the Hotel Intercontinental, has done such a solid business since it was built in 1976 that the owners decided to go ahead with building the disco next door.

Most of the clientele is expected to come from the hotel, which with its pyramid design was one of only two high-rise buildings that escaped damage or destruction during the earthquake.