Peter Allen’s career as a real estate developer can be traced back to his days as a college student, selling homes in the summers on farmland his grandfather developed with single-family detached housing beginning in the summer of 1964.

But it was the Vietnam era.

After graduating from DePauw University in 1967, it was his four years in the U.S. Navy — two on a destroyer, two spent teaching the safe handling of nuclear weapons — that perhaps launched him into the arena where he may be most influential: the classroom.

Allen, 76, is retiring after the fall semester as a University of Michigan lecturer on real estate development, having taught in what is now the Stephen M. Ross School of Business as well as the A. Alfred Taubman College of Architecture and Urban Planning for four decades, seeing some 4,000 students cross his gradebook.

“I was always teaching bright, young people headed all over the globe,” said Allen.

Although teaching was always a part-time position for him, never shedding his development hardhat for academia completely, he nonetheless didn’t let that dampen his passion for the lectern, former students say.

Those thousands of pupils range from some of the most influential in the business nationally to long-eminent local developers, from behind-the-scenes powerbrokers to emerging talent in and around Detroit, in the private, public and not-for-profit sphere.

He peppers conversations with their achievements and accolades. Jeff did this while a young student, just a junior surrounded by grad students, more than 30 years ago, Allen said. Hannah did that, Alex is up to this, Myles and Clarke and Dang pulled off that.

And then there is Sterling Heights native Omar Uddin, a recent former student who is now an intern with Allen, working on Allen’s next initiative, the Equitable Ann Arbor Land Trust, focusing on affordable housing in Ann Arbor.

Uddin’s dream: working on real estate development to the east in Detroit.

His dream is much like many of those who have gone through his course starting in 1981, when Allen was talking about things like walkability and large cities when so many had fled them for the suburbs.

“While Peter served generations of students formally as a professor, I think he also played a role as a kind of Willy Wonka of commercial real estate, inspiring generations of students with the potential of buildings and public spaces, encouraging them to use their brains and hearts and imaginations to build great places — and build wealth in the process,” said Hannah Mae Merten, urban innovation and strategy director with Dan Gilbert’s Bedrock LLC real estate company.