It’s a winter’s day, and Larry Millett, career newspaperman and historical-mystery novelist, is leading a walking tour of downtown St. Paul. Millett has pepper-colored hair, with a dash of salt here and there, and subscribes to the novelist’s school of fashion: black turtleneck, rimless glasses, mussed corduroys. He has opted for an aerial tour of sorts, threading his way through the skyways, pausing at each intersection to debate which way to go next. “My skyway skills are rusty,” he apologizes. “I want to be sure you get the best view.”

Tucked under his arm is Lost Twin Cities, the urtext of local urban historians and centenarians looking for the disappeared neighborhoods of their youth, a time when the clamor of hooves and peal of trolley bells still filled the alleys. But Millett, who wrote Lost Twin Cities during his tenure as the Pioneer Press’s architecture critic, is hardly consulting it. Imagine a temporal Google Street View that lets you wander the streets of fin-de-siecle St. Paul, gliding over trolley tracks and past Gothic Victorian mansions, pale Kasota stonework, terracotta and pressed-metal ornamentation, step gables, and plate-glass windows wide as a financier’s outstretched arms. Welcome to Larry Millett’s brain.