Millett worked at the Pioneer Press from 1972 until 1984 when he had an opportunity to study architecture at the University of Michigan in Ann Arbor.
He has written articles for several historical and architectural magazines in the Midwest, mostly focusing on works by Prairie School architects including Louis Sullivan and Frank Lloyd Wright.
Millett's Lost Twin Cities is probably the best known of his works in the Minneapolis-St. Paul region largely because KTCA, a local public television station, created a video documentary by the same name which covered a few of the buildings in the book.
The video was narrated by Dave Moore, a noted area TV journalist, and is often replayed when the station is running a pledge drive.
In 2014, Millet was interviewed by Peter Shea for the Institute for Advanced Study at the University of Minnesota in the Twin Cities.