JUANA DIAZ, Puerto Rico — In recent weeks, a structure resembling a flying saucer has been seen on a hill in this small village on the south side of the island. At dusk some days, its colored lights are visible from the main highway, causing traffic to almost come to a stop. Curious passers-by who venture off the highway discover that the structure, which appears to be solidly grounded, makes a four-tone sound like the greeting of the mother ship in “Close Encounters of the Third Kind.”

The tone poem is muted, but the colored lights and the blinking strobe on the dome make the house hard to miss, which is exactly as the owner wishes. For this is a tale more Gatsbyesque than intergalactic, although the blinking light in this case is not green or at the end of a pier, but lavender and announcing itself to the beloved and the cosmos.

The story of a home 40 years in the making, however, is not one to be rushed, so let us begin by introducing the protagonist, who hails, of course, from a distant land: the city of Ponce, 20 minutes down the road. His name is Roberto Sanchez Rivera, and he is 58, a retired teacher of industrial arts.

As the reporter does not speak Rivera’s native tongue, his girlfriend, Maria Martinez, a 56-year-old secretary at the Internal Revenue office in Isabela, who grew up in New York and has been seeing Rivera for two years, agrees to translate.

Those light fixtures, which Rivera added a few months ago at the base of the house, what are they made of?

“Salad bowls from the dollar store,” Martinez says. “I don’t know if they were $1.99 or $2.99.”

She calls to Rivera, who has ducked inside the house for a moment. “Roberto, a como le costaron los bowls de ensalada?” Then, to the reporter: “$1.99.”

“When he first started the lighting, he would walk all the way down to the corner and see how it looked,” Martinez says, as she and her son, Leandro, 24, and Rivera move into the house to sit at the kitchen table, which hovers several feet off the floor. “On three occasions he went down to the corner. Then he would see the attitude of the people when he turned on the lights — they wouldn’t know he was the owner of the house — and he would hear, ‘That looks better now,’ ‘Yeah,’ ‘Right.’”

Wow, they really do walk among us.

What about the four-tone beep, which, it turns out, actually is from “Close Encounters of the Third Kind”?

“He downloaded it from the Internet,” Martinez says. You might think that a fellow who builds a house in the shape of a spaceship would believe in visitors from outer space, but that is not the case. Rivera is not even particularly interested in movies about outer space, and often confuses “Close Encounters” with, as he puts it, “the one with the finger … ‘E.T.’”

He is simply a creative man, Martinez insists. Back in high school, he decided that one day he would build a house that was unlike any other. And after getting a degree in fine arts and studying industrial design, he had the ability to do that.

Rivera, who has the soul of an artist, bought the property where his house stands for $95,000 in 2002 and was able to build a three-bedroom, two-bathroom home on it for about $150,000, using discount-store knickknacks and discarded auto parts. “Repurposed” is too weak a word to do justice to Rivera’s ingenuity when confronted with a scrap of tin.

Those metallic boxes on the flying saucer’s dome, which suggest a sophisticated communications system or perhaps a weapon that could smash our sorry planet into smithereens? Ashtrays from the dollar store (Rivera used about 200).

In the guest bathroom, the ceiling is made from bath towels, pulled taut and shellacked. There is also an arresting painting by Rivera that shows an older man with his arm around a young man’s shoulder and, in the background, a long-haired woman who has turned away. The young man has a prominent tear running down his cheek.

“The picture is the story of this house,” Martinez says, translating for Rivera, who stands in the doorway. “The older man is his teacher, who betrayed him by telling lies. The woman was another student. Rivera was her boyfriend. They lasted about three months. They broke up; she told her mother he would never be anything in life.”

That was what inspired Rivera to build this house, Martinez continues. “He wanted to do it in a certain spot, so that if she were to travel she would see it day in and day out and regret those words.”

Ah, yes, the 40-year-old cuts to the heart are the ones that hang you up the most.

Rivera was a poor child, one of 12, whose father was the superintendent of a sugar cane mill, Martinez continues. When he was in high school, he went on a field trip and saw a house being built in the shape of a boat, which made a big impression on him. This was an era when there was much talk of UFOs, or as they’re called here, OVNIs, for Objeto Volador No Identificado.

The woman in the painting, whom Rivera declines to name, went to high school with him, and he sent her little love notes with pictures of flying saucers, promising that one day he would build a house shaped like that. Later, when they were studying at the Pontifical Catholic University in Ponce, Rivera and the young woman started going out.

“It ended because she wrote him a letter saying she did not want to continue the relationship, because she didn’t love him anymore,” Martinez says, translating for Rivera. “It was the mother who explained to him that her daughter had said that he would never amount to anything in life. He was shocked. He used to live on the 13th floor, and he wanted to throw himself off, but he held himself back and said, ‘No, I’m going to show her, this person, I’m going to work that much harder to show her who I am.’”

Martinez is translating matter of factly, although Rivera is speaking with emotion. “It motivated him more,” she says. “He just picked himself up and decided that someday she will hear about him.”

So that’s why he bought this piece of property, which can be seen from the road?

“Es y so! This is so!” puts in Rivera, who speaks some English.

Martinez seems very calm translating all of this, she is told. Doesn’t it make her jealous?

“Yes,” she says, it cuts her up inside. But Rivera no longer has feelings for the woman.

The last time he saw her was four years ago, Martinez says, resuming her translation. He had been married, had two children and was divorced by then. She called him and he invited her to come see the house. It was in its first stage — a house in the shape of an octagon — but still, the woman was impressed.

Rivera wanted her to see where he lived, so when she drove by she would know it was his house, Martinez says. He also knew that this would be the only time she visited. Although the woman was now interested in him, Rivera no longer wanted anything to do with her.

Let’s move on, then, to the current love story. How did Rivera meet Martinez, who had come to Puerto Rico after a divorce to make a fresh start?

She was out dancing with a group of friends, Martinez says. Their eyes met and they both froze. Later, he asked her to dance, but he was so shy he could barely look at her. When she left that night, he said, “Wait a minute,” and grabbed a napkin, twisting it into the shape of a rose.

“That’s how he stole my heart,” Martinez says. “With a rose.”