Sometimes Richard Landry can’t believe how well his life and career have turned out.

After all, what if he had stayed in Quebec and accepted the teaching job he was offered after architecture school? What if Alberta hadn’t hit a recession, prompting him to leave the small commercial firm where he spent his early professional years and strike out for Los Angeles, a city he chose based on the climate and the fact that it was 1984 and everyone was talking about the Summer Olympics? And what if, when he arrived in town a stranger and began looking up architects in the phone book, Frank Gehry had returned his call?

Gehry did not return Landry’s call. Instead, he was hired at the firm R. Duell & Associates, which specialized in designing theme parks like Magic Mountain, a job he described as “pure fun, pure fantasy.” Bright and eager to please, he went on to work for a small firm doing residential projects in a new gated community called Beverly Park that overlooks Beverly Hills. Then a treeless bowl of dirt, Beverly Park would come to epitomize the sealed-off, rich person’s bubble in a city full of them, a smog-free haven for private-equity billionaires, superstar athletes and Sylvester Stallone, a client.

So when Landry shakes his head now and says, “I have a hard time when I reflect on it and ask, ‘How did I end up here?’” you can almost believe that it was fate that brought him west and gave him the temperament and skill set to design dream homes for an age of economic exuberance.

Thirty years after arriving with all of his possessions stuffed in his Honda, Landry, 57, is one of the most sought-after high-end residential architects in Southern California and beyond. His clients are the superrich, the super-famous and, frequently, both.

His homes would give feudal-age rulers property envy. There’s the 12,500-square-foot French-inspired home in Brentwood that he designed for Tom Brady and Gisele Bündchen, with what Architectural Digest described as an actual moat around it. The 28-bedroom, 32-bath, glass, steel and stone compound tumbling down a Bel-Air hillside was named the Robb Report’s “Ultimate Home” in 2011.

And the 30,000-square-foot European manor, with a basketball court and two Jacuzzis, where actor Mark Wahlberg just took up residence in Beverly Park?

“When he called me, he said, ‘Richard, I’ve been following you for years. I’m so glad now you can do my house,’” Landry said. “What a nice guy. We had so much fun.”

Landry is something of a court architect for the hilltop fief, having designed several homes in Beverly Park, including a sprawling villa currently owned by a handbag mogul (now on the market for $25 million) and a 15,000-square-foot chateau once owned by “Real Housewives” star Lisa Vanderpump.

By servicing the prosperous, Landry has himself prospered. His firm, Landry Design Group, employs close to 50 people who work in an office building that he purchased last year and has dozens of projects in various stages around the globe.

“I could retire today and be fine the rest of my life,” he said. “It’s such a great place to be.”

Of course, life isn’t a total cruise. Landry can no longer get replacement parts for his $100,000 electric-powered sports car, because the company that made it went bankrupt. More troubling is the criticism that has come with being the favored architect of the 1 percent. He has been called the “mansion architect,” the “king of the tasteless megamansion” and, as one online commenter dubbed him, a purveyor of the “gigamansion.”

The real estate blog Curbed has been his most relentless critic, calling Landry’s houses “unnecessarily over the top” and “ugly” and suggesting that “if the plebs knew more about what he was up to” it could “spark America’s populist revolution.”

The homes he designs are, indeed, overt displays of wealth, expressed in loggias and porte cochères; home theaters and double-height foyers; Italian marble and specially aged, acid-washed limestone. Even the two books he published to showcase them are as thick as marble slabs.

But Landry, who had a plebeian childhood as the son of a carpenter in rural Quebec (and didn’t learn English until he was 20), isn’t interested in class warfare. Whether the haves should practice self-restraint for the betterment of society is a matter for sociologists. “Is it right or wrong for somebody to build a big home?” he said. “I’m not the one to answer that question.”

Landry’s approach isn’t to tell his clients that a sustainable vegetable garden behind a ginormous house is a little ridiculous. Or to impose on them his singular vision, Frank Lloyd Wright-style. Above all, he wants to make them happy. To design homes suited to their individual needs and whims. “There are a million things I could do,” he said. “This is about you. Let’s talk about what you need.”

James Magni, a Los Angeles-based interior designer who works frequently with Landry, said he is unlike any other architect in his chameleon-like ability to design to the client’s wishes. “Most architects have one stylistic philosophy they work in,” Magni said. “His style changes from project to project and client to client.”

Although Landry is known primarily for faux-European piles, he does not have a signature look — or size. His firm has done plenty of gigantic chateaus of the Loire Valley but also relatively modest Spanish-style beach homes, mid-century-inspired houses, vernacular barns, swooping modern dwellings, austere architecture and remodels of existing homes.

“Some of the celebrity clients we work with don’t have any privacy outside of their home,” he said. “So let them have a home theater or a bowling alley. It’s not about justifying that somebody needs a 30,000-square-foot home.”

Or 40,000. Which is the size of a French country estate he designed. The house has a mansard roof topped with what looks like an entire quarry of slate. It has a guesthouse larger than many Americans’ homes. And running between that guesthouse and the main residence is a full-on “old” cobblestone street, just like the ones in Europe.

Although Landry wants to make it clear that he isn’t the megamansion guy — that he does all styles and sizes — standing before this enormous house his eyes sparkled. “This is great,” he couldn’t help saying.

Your eyes might sparkle too if you were an architect given some of the most prime land in the country, two acres atop the lush hills of west Los Angeles, and from thin air conjured a castle.

No doubt Landry’s critics would look at the place and find it lacking. And you know what? He agrees.

“I honestly believe we haven’t done our best work yet,” Landry said.